The Torques Acting on Accreting Millisecond X-Ray Pulsars in the Outburst and Quiescent States, and During the Long-Term Evolution
Pith reviewed 2026-05-20 15:19 UTC · model grok-4.3
The pith
A standard torque model from low-mass X-ray binaries accounts for the observed spin-up, spin-down, and long-term slowing of five accreting millisecond X-ray pulsars.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The torques produced by the disc-magnetosphere interaction, the magnetic dipole radiation, and the mass accretion are compatible with the X-ray luminosity and rotational properties of the sources in their outburst and quiescent states, and during the resultant long-term evolution.
What carries the argument
The torque model combining disc-magnetosphere interaction torques with magnetic dipole radiation and mass-accretion torques, applied to outburst and quiescent states to track net angular momentum changes.
If this is right
- Most of the systems spin up during outbursts and spin down in quiescence.
- The sources experience net spin-down over long timescales.
- The model reproduces the observed X-ray luminosities and rotational properties without requiring major adjustments.
- Gravitational radiation torques remain possible but are not required by current data.
Where Pith is reading between the lines
- If the model holds, these five sources are confirmed as late-stage low-mass X-ray binaries approaching the end of mass transfer.
- Improved timing observations with reduced noise could distinguish gravitational-wave spin-down from the magnetic and accretion torques.
- The same torque framework may apply to other transient accreting pulsars once bolometric corrections are refined.
Load-bearing premise
The torque model developed for typical low-mass X-ray binary behavior applies directly to these five accreting millisecond X-ray pulsars, and bolometric corrections for X-ray luminosity are accurate enough to separate the different torque contributions.
What would settle it
A measurement showing that the observed spin frequency derivative during an outburst or quiescence period deviates significantly from the value predicted by the combined disc-magnetosphere, dipole, and accretion torques at the measured X-ray luminosity.
Figures
read the original abstract
Accreting millisecond X-ray pulsars (AMXPs) are transient X-ray sources likely to be in the final evolutionary phases of low-mass X-ray binaries (LMXBs). In this work, we have investigated the torque and X-ray luminosity variations of five AMXPs during outburst and quiescence, using a model previously employed to explain some typical behaviours of LMXBs. Most of these systems spin up in the outburst state and spin down in quiescence, while they slow down on the long term. We have obtained reasonable results with the model in agreement with these observations. We have found that the torques produced by the disc-magnetosphere interaction, the magnetic dipole radiation, and the mass accretion are compatible with the X-ray luminosity and rotational properties of the sources in their outburst and quiescent states, and during the resultant long-term evolution. Nevertheless, our results are not sufficient to rule out the spin-down contribution of the gravitational radiation torques due to significant timing noise and uncertainties about the bolometric corrections for X-ray luminosity during the outbursts of some sources.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript applies a torque model previously used for LMXBs to five AMXPs, analyzing variations in torque and X-ray luminosity during outburst and quiescence. It reports that the combined effects of disc-magnetosphere interaction, magnetic dipole radiation, and mass accretion torques are compatible with the observed spin-up in outburst, spin-down in quiescence, and long-term spin-down, while noting that timing noise and bolometric correction uncertainties prevent ruling out gravitational radiation contributions.
Significance. If the compatibility claims can be made robust against the acknowledged uncertainties, the work would support extending standard accretion torque models to the AMXP population and clarify their evolutionary connection to LMXBs. However, the current analysis provides only weak constraints, limiting its broader impact on understanding spin evolution or torque balance in these systems.
major comments (2)
- [Abstract] Abstract: The central claim that the torques 'are compatible with the X-ray luminosity and rotational properties' is not load-bearing because the text itself states that 'significant timing noise and uncertainties about the bolometric corrections for X-ray luminosity during the outbursts of some sources' prevent ruling out gravitational radiation. A factor-of-two variation in bolometric corrections (common in AMXP studies) would shift the inferred accretion torque enough to accommodate or exclude the modeled components within the reported noise, rendering the test non-discriminating.
- [Model application section (likely §2–3)] Model application section (likely §2–3): The manuscript does not specify whether the torque equations (disc-magnetosphere, dipole radiation, accretion) are used with independently measured parameters or adjusted to fit the observed spin derivatives and luminosities for the five sources. Without explicit parameter tables or a sensitivity analysis to bolometric corrections and timing noise, it is unclear if the 'reasonable results' constitute an independent test or a post-hoc consistency check.
minor comments (2)
- The full data analysis details, including how outburst and quiescent luminosities and spin derivatives were extracted for each of the five sources, should be expanded or referenced to allow reproducibility.
- Clarify the exact form of the disc-magnetosphere torque formula employed and any assumptions about the magnetospheric radius relative to the corotation radius.
Simulated Author's Rebuttal
We thank the referee for the careful review and constructive feedback. We respond to each major comment below, indicating where revisions will be made to clarify the analysis and strengthen the presentation.
read point-by-point responses
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Referee: [Abstract] Abstract: The central claim that the torques 'are compatible with the X-ray luminosity and rotational properties' is not load-bearing because the text itself states that 'significant timing noise and uncertainties about the bolometric corrections for X-ray luminosity during the outbursts of some sources' prevent ruling out gravitational radiation. A factor-of-two variation in bolometric corrections (common in AMXP studies) would shift the inferred accretion torque enough to accommodate or exclude the modeled components within the reported noise, rendering the test non-discriminating.
Authors: We agree that the acknowledged uncertainties in timing noise and bolometric corrections limit the strength of the conclusions, which is why the manuscript already states that gravitational radiation torques cannot be ruled out. The analysis demonstrates consistency of the standard torques with the data within those uncertainties rather than a strong exclusion of alternatives. We will revise the abstract to emphasize this as a consistency check and add a brief quantitative discussion of how factor-of-two changes in bolometric corrections propagate into the torque balance. revision: yes
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Referee: [Model application section (likely §2–3)] Model application section (likely §2–3): The manuscript does not specify whether the torque equations (disc-magnetosphere, dipole radiation, accretion) are used with independently measured parameters or adjusted to fit the observed spin derivatives and luminosities for the five sources. Without explicit parameter tables or a sensitivity analysis to bolometric corrections and timing noise, it is unclear if the 'reasonable results' constitute an independent test or a post-hoc consistency check.
Authors: The torque model is applied using parameters drawn from independent literature measurements (spin frequencies, orbital periods, and magnetic field estimates from other observables) for each source, with the resulting torques then compared to the observed spin derivatives and luminosities. To remove ambiguity, we will add an explicit table of all input parameters and their references, together with a sensitivity analysis showing the effect of plausible variations in bolometric corrections and timing noise amplitudes on the compatibility conclusions. revision: yes
Circularity Check
No circularity: established torque model applied to new sources with compatibility check
full rationale
The paper applies a torque model previously employed for LMXBs to five AMXPs and reports that disc-magnetosphere, dipole radiation, and accretion torques are compatible with observed X-ray luminosities and spin properties in outburst, quiescence, and long-term evolution. This constitutes an application and consistency test of an external model rather than a derivation that reduces to its own inputs by construction. No equations are shown to be self-definitional, no fitted parameters are renamed as independent predictions, and the cited model is treated as prior independent work. The abstract explicitly notes limitations from timing noise and bolometric corrections, confirming the analysis does not force results tautologically. The derivation chain remains self-contained against external benchmarks.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption The torque model previously employed for LMXBs applies directly to these AMXPs
Lean theorems connected to this paper
-
IndisputableMonolith/Cost/FunctionalEquation.leanwashburn_uniqueness_aczel unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
the torques produced by the disc-magnetosphere interaction, the magnetic dipole radiation, and the mass accretion are compatible with the X-ray luminosity and rotational properties
-
IndisputableMonolith/Foundation/AlphaCoordinateFixation.leanJ_uniquely_calibrated_via_higher_derivative unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
Γ = Ṁ* √(G M r_in) − μ²/r_in³ (Δr/r_in) − 2μ²Ω*³/(3c³)
What do these tags mean?
- matches
- The paper's claim is directly supported by a theorem in the formal canon.
- supports
- The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
- extends
- The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
- uses
- The paper appears to rely on the theorem as machinery.
- contradicts
- The paper's claim conflicts with a theorem or certificate in the canon.
- unclear
- Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.
Reference graph
Works this paper leans on
-
[1]
Black holes in binary systems. Observational appearance. , year = 1973, volume = 24, pages =
work page 1973
-
[2]
Juhan Frank and Andrew King and Derek J. Raine , isbn =. Cambridge University Press , pages =
-
[3]
Monthly Notices of the Royal Astronomical Society , keywords =
Guillaume Dubus and Jean Pierre Lasota and Jean Marie Hameury and Phil Charles , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[4]
New Astronomy Reviews , keywords =
Jean Pierre Lasota , doi =. New Astronomy Reviews , keywords =
-
[5]
M. A. Alpar and A. F. Cheng and M. A. Ruderman and J. Shaham , doi =. Nature , keywords =
-
[6]
Current Science , year = 1982, month = dec, volume =
On the origin of the recently discovered ultra-rapid pulsar. Current Science , year = 1982, month = dec, volume =
work page 1982
-
[8]
A. Papitto and M. T. Menna and L. Burderi and T. Di Salvo and A. Riggio , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[11]
Monthly Notices of the Royal Astronomical Society , keywords =
Marek Gierliński and Juri Poutanen , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[12]
A. Sanna and F. Pintore and A. Riggio and S. M. Mazzola and E. Bozzo and T. Di Salvo and C. Ferrigno and A. F. Gambino and A. Papitto and R. Iaria and L. Burderi , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[13]
M. Falanga and L. Kuiper and J. Poutanen and D. K. Galloway and E. W. Bonning and E. Bozzo and A. Goldwurm and W. Hermsen and L. Stella , doi =. Astronomy and Astrophysics , keywords =
-
[14]
A. Papitto and A. Riggio and T. Di Salvo and L. Burderi and A. D'Aì and R. Iaria and E. Bozzo and M. T. Menna , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[15]
Brynmor Haskell and Nathalie Degenaar and Wynn C.G. Ho , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[16]
E. Bozzo and C. Ferrigno and M. Falanga and S. Campana and J. A. Kennea and A. Papitto , doi =. Astronomy and Astrophysics , keywords =
-
[18]
D. Altamirano and A. Watts and M. Linares and C. B. Markwardt and T. Strohmayer and A. Patruno , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[19]
Ray and Peter Bult and Deepto Chakrabarty and Gaurava K
Mason Ng and Paul S. Ray and Peter Bult and Deepto Chakrabarty and Gaurava K. Jaisawal and Christian Malacaria and Diego Altamirano and Zaven Arzoumanian and Keith C. Gendreau and Tolga Güver and Matthew Kerr and Tod E. Strohmayer and Zorawar Wadiasingh and Michael T. Wolff , doi =. The Astrophysical Journal Letters , month =
-
[20]
Armas Padilla, M and R. Wijnands and N. Degenaar , doi =. Monthly Notices of the Royal Astronomical Society: Letters , keywords =
-
[21]
M. Falanga and L. Kuiper and J. Poutanen and E. W. Bonning and W. Hermsen and T. Di Salvo and P. Goldoni and A. Goldwurm and S. E. Shaw and L. Stella , doi =. Astronomy and Astrophysics , keywords =
-
[22]
P. G. Jonker and S. Campana and D. Steeghs and M. A.P. Torres and D. K. Galloway and C. B. Markwardt and D. Chakrabarty and J. Swank , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[23]
A. Paizis and M. A. Nowak and J. Wilms and T. J.L. Courvoisier and K. Ebisawa and J. Rodriguez and P. Ubertini , doi =. Astronomy and Astrophysics , keywords =
-
[24]
A. Papitto and A. Riggio and L. Burderi and T. Di Salvo and A. D'Aí and R. Iaria , doi =. Astronomy and Astrophysics , keywords =
-
[25]
A. Sanna and F. Pintore and E. Bozzo and C. Ferrigno and A. Papitto and A. Riggio and T. Di Salvo and R. Iaria and A. D'Aì and E. Egron and L. Burderi , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[26]
Jacob M. Hartman and Duncan K. Galloway and Deepto Chakrabarty , doi =. Astrophysical Journal , keywords =
-
[28]
The Astrophysical Journal , keywords =
Alessandro Patruno , doi =. The Astrophysical Journal , keywords =
-
[30]
The Astrophysical Journal , month =
Alessandro Patruno , doi =. The Astrophysical Journal , month =
-
[32]
Monthly Notices of the Royal Astronomical Society , keywords =
Dipanjan Mukherjee and Peter Bult and Michiel Van Derklis and Dipankar Bhattacharya , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[33]
Duncan K. Galloway and Craig B. Markwardt and Edward H. Morgan and Deepto Chakrabarty and Tod E. Strohmayer , doi =. The Astrophysical Journal , month =
-
[34]
The Astrophysical Journal , keywords =
Sudip Bhattacharyya and Deepto Chakrabarty , doi =. The Astrophysical Journal , keywords =
-
[35]
C. R. D'Angelo , doi =. Monthly Notices of the Royal Astronomical Society , keywords =
-
[36]
Luciano Burderi and Andrea Possenti and Francesca D ' Antona and Tiziana Di Salvo and Marta Burgay and Luigi Stella and Maria Teresa Menna and Rosario Iaria and Sergio Campana and Nichi D'amico , journal =
-
[37]
Gendreau and Sebastien Guillot and Wynn C
Peter Bult and Diego Altamirano and Zaven Arzoumanian and Deepto Chakrabarty and Keith C. Gendreau and Sebastien Guillot and Wynn C. G. Ho and Gaurava K. Jaisawal and Steven Lentine and Craig B. Markwardt and Son N. Ngo and John S. Pope and Paul. S. Ray and Maxine R. Saylor and Tod E. Strohmayer , doi =. The Astrophysical Journal , month =
-
[38]
A. Papitto and E. Bozzo and C. Sanchez-Fernandez and P. Romano and D. F. Torres and C. Ferrigno and J. J.E. Kajava and E. Kuulkers , doi =. Astronomy and Astrophysics , keywords =
-
[39]
The Astronomer's Telegram , keywords =
IGR J00291+5934 is a 598 Hz X-ray Pulsar. The Astronomer's Telegram , keywords =
-
[44]
L. Burderi and T. Di Salvo and M. T. Menna and A. Riggio and A. Papitto , doi =. The Astrophysical Journal , keywords =
-
[46]
Markwardt and Deepto Chakrabarty , doi =
Manuel Linares and Rudy Wijnands and Michiel van der Klis and Hans Krimm and Craig B. Markwardt and Deepto Chakrabarty , doi =. The Astrophysical Journal , month =
-
[48]
The Astronomer's Telegram , keywords =
A new hard X-ray transient discovered by INTEGRAL: IGR J17494-3030. The Astronomer's Telegram , keywords =
-
[49]
The Astronomer's Telegram , keywords =
2012 Chandra Non-Detection of the Fading X-ray Transient IGR J17494-3030. The Astronomer's Telegram , keywords =
work page 2012
-
[50]
The Astronomer's Telegram , keywords =
NICER detection of 376 Hz X-ray pulsations from IGR J17494-3030. The Astronomer's Telegram , keywords =
-
[53]
C. B. Markwardt and H. A. Krimm and J. H. Swank , journal =
-
[54]
I. A. Mereminskiy and S. A. Grebenev and R. A. Krivonos and R. A. Sunyaev , journal =
-
[55]
A. Sanna and F. Pintore and A. Riggio and L. Burderi and A. F. Gambino and K. C. Gendreau and Z. Arzoumanian and P. M. Bult and T. di Salvo and R. Iaria and C. Ferrigno and E. Bozzo and A. Papitto , journal =
-
[56]
The Astronomer's Telegram , keywords =
Chandra non-detection of the newly discovered Millisecond X-ray Pulsar SWIFT J1756.9-2508. The Astronomer's Telegram , keywords =
-
[57]
The Astronomer's Telegram , keywords =
INTEGRAL discovered a new hard X-ray source: IGRJ17511-3057. The Astronomer's Telegram , keywords =
-
[58]
The Astronomer's Telegram , keywords =
RXTE and Swift: IGR J17511-3057 fading, XTE J1751-305 detected. The Astronomer's Telegram , keywords =
-
[59]
The Astronomer's Telegram , keywords =
INTEGRAL detects a new outburst from the millisecond X-ray pulsar IGR J17511-3057. The Astronomer's Telegram , keywords =
-
[60]
The Astronomer's Telegram , keywords =
The onset of a new outburst from the millisecond X-ray pulsar IGR J17511-3057 as detected by INTEGRAL. The Astronomer's Telegram , keywords =
-
[61]
The Astronomer's Telegram , keywords =
IGR J00291+5934, a new X-ray transient discovered with INTEGRAL. The Astronomer's Telegram , keywords =
-
[62]
Lars Bildsten and Deepto Chakrabarty and John Chiu and Mark H. Finger and Danny T. Koh and Robert W. Nelson and Thomas A. Prince and Bradley C. Rubin and D. Matthew Scott and Mark Stollberg and Brian A. Vaughan and Colleen A. Wilson and Robert B. Wilson , doi =. The Astrophysical Journal Supplement Series , keywords =
-
[67]
A. Patruno and C. B. Markwardt and T. E. Strohmayer and J. H. Swank and S. E. Smith and D. Pereira , journal =
-
[68]
D. Chakrabarty and J. H. Swank and C. B. Markwardt and E. Smith , journal =
-
[69]
A. Sanna and F. Pintore and A. Riggio and L. Burderi and T. Di Salvo and R. Iaria and F. Scarano and A. Papitto and E. Bozzo , journal =
- [82]
- [83]
-
[86]
Alpar M. A., Cheng A. F., Ruderman M. A., Shaham J., 1982, @doi [Nature] 10.1038/300728A0 , 300, 728
-
[87]
Altamirano D., Watts A., Linares M., Markwardt C. B., Strohmayer T., Patruno A., 2010, @doi [Monthly Notices of the Royal Astronomical Society] 10.1111/j.1365-2966.2010.17369.x , 409, 1136
-
[88]
Archibald A. M., et al., 2009, @doi [Science] 10.1126/science.1172740 , https://ui.adsabs.harvard.edu/abs/2009Sci...324.1411A 324, 1411
-
[89]
Armas Padilla M., Wijnands R., Degenaar N., 2013, @doi [Monthly Notices of the Royal Astronomical Society: Letters] 10.1093/mnrasl/slt119 , 436
-
[90]
Bahramian A., Degenaar N., 2022, Low-Mass X-ray Binaries. Springer Nature Singapore, Singapore, pp 1--62, @doi 10.1007/978-981-16-4544-0_94-1 , https://doi.org/10.1007/978-981-16-4544-0_94-1
-
[91]
Baldovin C., et al., 2009, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2009ATel.2196....1B 2196, 1
work page 2009
-
[92]
Bassa C. G., et al., 2014, @doi [ ] 10.1093/mnras/stu708 , https://ui.adsabs.harvard.edu/abs/2014MNRAS.441.1825B 441, 1825
-
[93]
Bhattacharyya S., Chakrabarty D., 2017, @doi [The Astrophysical Journal] 10.3847/1538-4357/835/1/4 , 835, 4
-
[94]
Bildsten L., 1998, @doi [The Astrophysical Journal] 10.1086/311440 , 501, L89
-
[95]
Bildsten L., et al., 1997, @doi [The Astrophysical Journal Supplement Series] 10.1086/313060/XML , 113, 367
-
[96]
Boissay R., et al., 2012, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2012ATel.3984....1B 3984, 1
work page 2012
-
[97]
Bozzo E., et al., 2015, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2015ATel.7275....1B 7275, 1
work page 2015
-
[98]
Bult P., et al., 2018, @doi [The Astrophysical Journal] 10.3847/1538-4357/aad5e5 , 864, 14
-
[99]
Burderi L., Salvo T. D., Menna M. T., Riggio A., Papitto A., 2006, @doi [The Astrophysical Journal] 10.1086/510666/FULLTEXT/ , 653, L133
-
[100]
Burderi L., et al., 2007, @doi [The Astrophysical Journal] 10.1086/510659 , 657, 961
-
[101]
Chakrabarty D., Jonker P. G., Markwardt C. B., 2013, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2013ATel.4886....1C 4886, 1
work page 2013
-
[102]
R., 2017, @doi [Monthly Notices of the Royal Astronomical Society] 10.1093/MNRAS/STX1306 , 470, 3316
D'Angelo C. R., 2017, @doi [Monthly Notices of the Royal Astronomical Society] 10.1093/MNRAS/STX1306 , 470, 3316
-
[103]
De Falco V., Kuiper L., Bozzo E., Galloway D. K., Poutanen J., Ferrigno C., Stella L., Falanga M., 2017, @doi [ ] 10.1051/0004-6361/201629575 , https://ui.adsabs.harvard.edu/abs/2017A&A...599A..88D 599, A88
-
[104]
Di Salvo T., Sanna A., 2022, in Bhattacharyya S., Papitto A., Bhattacharya D., eds, , Millisecond Pulsars. Springer International Publishing, Cham, pp 87--124, @doi 10.1007/978-3-030-85198-9_4 , https://doi.org/10.1007/978-3-030-85198-9_4
-
[105]
Di Salvo T., Papitto A., Marino A., Iaria R., Burderi L., 2024, Low-Magnetic-Field Neutron Stars in X-ray Binaries. Springer Nature Singapore, Singapore, pp 4031--4103, @doi 10.1007/978-981-19-6960-7_103 , https://doi.org/10.1007/978-981-19-6960-7_103
-
[106]
Dubus G., Lasota J. P., Hameury J. M., Charles P., 1999, @doi [Monthly Notices of the Royal Astronomical Society] 10.1046/J.1365-8711.1999.02212.X/2/303-1-139-FIG010.JPEG , 303, 139
work page doi:10.1046/j.1365-8711.1999.02212.x/2/303-1-139-fig010.jpeg 1999
-
[107]
Eckert D., Walter R., Kretschmar P., Mas-Hesse M., Palumbo G. G. C., Roques J.-P., Ubertini P., Winkler C., 2004, The Astronomer's Telegram, https://ui.adsabs.harvard.edu/abs/2004ATel..352....1E 352, 1
work page 2004
-
[108]
Ertan \"U ., 2017, @doi [Monthly Notices of the Royal Astronomical Society] 10.1093/MNRAS/STW3131 , 466, 175
-
[109]
Ertan \"U ., 2018, @doi [Monthly Notices of the Royal Astronomical Society: Letters] 10.1093/MNRASL/SLY089 , 479, L12
-
[110]
Ertan \"U ., 2021, @doi [Monthly Notices of the Royal Astronomical Society] 10.1093/MNRAS/STAA3378 , 500, 2928
-
[111]
Ertan \"U ., Alpar M. A., 2021, @doi [Monthly Notices of the Royal Astronomical Society: Letters] 10.1093/mnrasl/slab060 , 505, L112
-
[112]
Falanga M., et al., 2005, @doi [Astronomy and Astrophysics] 10.1051/0004-6361:20053472 , 444, 15
-
[113]
J., 2002, Cambridge University Press, 39, 398
Frank J., King A., Raine D. J., 2002, Cambridge University Press, 39, 398
work page 2002
discussion (0)
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