Typed states for the displayed outbound observations.
Source: paper_references, paper_reference_links, observed 2026-08-15T17:17:54.421372Z
Paper Citation Record · LEDGER
As of 17 August 2026, this Paper Citation Record lists 67 of 67 outbound references and 0 inbound Pith citation observations for arXiv:2508.13341.
A citation records a reference. It does not transfer a finding from one paper to another.
Typed states for the displayed outbound observations.
Source: paper_references, paper_reference_links, observed 2026-08-15T17:17:54.421372Z
One-hop event checks from named stored sources.
Source: scholarly_work_events, retraction_status_cache, observed 2026-08-17T06:30:58.91139+00:00
Pith citing papers itemized under the disclosed page cap.
Source: paper_references, paper_reference_links
A source-named dated measurement, never combined with another source.
Source: cited_works
67 of 67 outbound references displayed
External citation measurements
No source-named external measurement is stored.
Observation 2b716f88-359f-4973-97c7-092076f5fe12 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Stationary Rotating Black Hole Exact Solution within Einstein--Nonlinear Electrodynamics
Reference 11
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation b7d4dd21-887f-4f23-947f-feb89cb561aa · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole AdS–dS stationary rotating black hole exact solution within Einstein-nonlinear electrodynamics,
Reference 12
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation b3986bf6-b53f-4068-ac2d-b4548e68a23a · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Nonlinear electromagnetic generalization of the Kerr-Newman solution with a cosmological con- stant,
Reference 13
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 3aca69ca-c684-475d-8c87-50224b62a2e9 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole First M87 Event Horizon Telescope Results. V . Physical Origin of the Asymmetric Ring,
Reference 14
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 0878f977-c16c-418c-8f6f-9007534e88b6 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way,
Reference 15
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation cf1dd18f-ec25-48a5-abdf-5d41791c8c31 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Analysis of a nonlinear electromagnetic generalization of the Reissner–Nordstr¨om black hole,
Reference 16
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 49bf5566-86ec-437b-b7ec-3a896372c903 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Remarks on a nonlinear electromagnetic extension in AdS Reissner-Nordstr¨om spacetime,
Reference 17
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 42bc0b8d-1770-43d5-9dbd-e06a711c65c7 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Extraction of Rotational Energy from a Black Hole,
Reference 18
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 5e55b613-46b1-42b0-be8d-e8cb90ff3382 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Observers in Kerr spacetimes: the ergoregion on the equatorial plane,
Reference 19
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 322d00ec-5476-4664-aac2-a2c5765e0bd5 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Global structure of the kerr family of gravitational fields,
Reference 20
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation c952aa8c-25dc-4b35-bc24-9a2dab960d59 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Chandrasekhar, The mathematical theory of black holes
Reference 21
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 313400ec-030d-4ef6-bf08-a3723d5fecb1 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Equatorial circular orbits in Kerr–Newman–de Sitter spacetimes,
Reference 22
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 9aaff571-6845-4376-bdea-4e3fbaf8a101 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Analytical solution of the geodesic equation in kerr-(anti-) de sitter space-times,
Reference 23
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 1bb0973b-8679-4c49-8f47-f06561d6ab00 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Light escape cones in local reference frames of kerr–de sitter black hole spacetimes and related black hole shadows,
Reference 24
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation cd7d657e-3137-4027-8899-318e486a9748 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Global structure of the Kerr family of gravitational fields,
Reference 25
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 207ba860-d6f5-44f6-97a3-7de39ca4d5b8 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Rotating Black Holes: Locally Nonrotating Frames, Energy Extraction, and Scalar Synchrotron Radiation,
Reference 26
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation e0899895-9bec-46eb-9061-e601dae235d2 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Timelike and null geodesics in the Kerr metric,
Reference 27
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 663fdbbc-0c0d-4105-98f9-33d1ddf89914 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Polar orbits in the Kerr space-time,
Reference 28
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 573b982d-aefb-40a8-afa2-a8a9e92fa093 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Using the Uncharged Kerr Black Hole as a Gravitational Mirror,
Reference 29
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation de8fc930-a48f-4dc1-8e27-5832edb4c0c2 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Spherical Photon Orbits Around a Kerr Black Hole,
Reference 30
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 0aea49c9-6835-4668-9643-5d629f8b8cb9 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole PHOTON RINGS AROUND KERR AND KERR-LIKE BLACK HOLES,
Reference 31
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation b6e18101-1c53-456e-942d-40a4ad57ae42 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Photon regions and shadows of kerr-newman-nut black holes with a cosmological constant,
Reference 32
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 70f7132d-0a80-4ee6-b0e2-496ac1014348 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Light propagation in a plasma on kerr spacetime: Separation of the hamilton-jacobi equation and calculation of the shadow,
Reference 33
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 5b2aa652-f79d-4cfa-92a4-21b3e17b1c05 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Spherical photon orbits in the field of Kerr naked singularities,
Reference 34
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation d0abc49f-340b-4b35-a1a2-e2f78c382773 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Universal interferometric signatures of a black hole’s photon ring,
Reference 35
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation bc45c86f-ef35-4058-98a8-cd114f8f76da · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Universal polarimetric signatures of the black hole photon ring,
Reference 36
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 82134dca-4dd9-4901-8b95-d4b22012620d · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Polarized image of equatorial emission in the kerr geometry,
Reference 37
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 91da4802-ca67-4bfa-aff4-fb15be8fadd2 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Testing gravity with black hole shadow subrings,
Reference 38
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 9519487b-726c-4d53-beee-57bfae4b7cf5 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Study of circular geodesics and shadow of rotating charged black hole surrounded by perfect fluid dark matter immersed in plasma,
Reference 39
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation e88f9037-f4e4-43cb-884c-c7a4f8fb232d · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Spherical photon orbits around a rotating black hole with quintessence and cloud of strings,
Reference 40
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation fac77378-0ef9-4ece-b45f-545071ac856b · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Investigating effects of dark matter on photon orbits and black hole shadows,
Reference 41
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 738776b1-2f7c-405c-97e6-a81b2bc7ab02 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Radii of spherical photon orbits around kerr-newman black holes,
Reference 42
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 0fb78a68-7932-4152-9408-b0eab88e2951 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Spherical orbits around Kerr-Newman and regular black holes,
Reference 43
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 5e5d4cbe-63bc-4cd6-a753-40d8f9e6b40e · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Black hole shadows, photon rings, and lensing rings,
Reference 44
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation e5c934b4-94c4-4abc-8f37-9d5207b421d7 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Analytical study of higher-order ring images of the accretion disk around a black hole,
Reference 45
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 86843a16-75d3-4612-8d56-81045624cbd8 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Shape of higher-order images of equatorial emission rings around a Schwarzschild black hole: Analytical description with polar curves,
Reference 46
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 68499b4f-fc95-46b0-9b12-92909fbd1851 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole The geometry of photon surfaces,
Reference 47
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation c14af646-6849-476f-8b17-9c3c13d02572 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Relativistic images of Schwarzschild black hole lensing,
Reference 48
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 8996a034-aecc-4ecd-86d6-bfca00864616 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Compactness of supermassive dark objects at galactic centers,
Reference 49
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 80fe8883-a446-49ca-8978-c130d085964a · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Rotating Black Holes: Locally Nonrotating Frames, Energy Extraction, and Scalar Synchrotron Radiation,
Reference 50
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 1b54663b-c997-4ff4-97e7-d102eea2ec7a · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Strong-field gravitational lensing by a Kerr black hole,
Reference 51
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 2a8d1f2b-6d6a-405a-b866-711274086f11 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Grenzebach, The Shadow of Black Holes, pp
Reference 52
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 0f546300-76bc-41e4-8317-f44afe416447 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Measurement of the Kerr Spin Parameter by Observation of a Compact Object’s Shadow,
Reference 53
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 7bcb5b92-cd8a-41c8-b3db-6f66d50a80f7 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Constraints on Barrow Entropy from M87* and S2 Star Observations,
Reference 54
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 7953387f-3734-40e0-91d4-8842f5a997b2 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Nonlinear electrodynamics effects on the black hole shadow, deflection angle, quasinormal modes and grey- body factors,
Reference 55
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 51052b7d-d970-4ec5-a68d-ccf9fd0cf4f7 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Parameter estimation of hairy Kerr black holes from its shadow and constraints from M87*,
Reference 56
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 0386dcaa-d678-431d-8e57-8d767f0b89d3 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Superradiant evolution of the shadow and photon ring of Sgr A *,
Reference 57
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 05a6264e-3fc6-4fff-8632-4946180f1653 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Tests of Loop Quantum Gravity from the Event Horizon Telescope Results of Sgr A*,
Reference 58
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation f2577385-186d-4d63-8179-162df05caa23 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Shadow of the Kerr-like black hole,
Reference 59
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation e82e911b-c7db-439f-99bb-b2ae3a3d4b00 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Shadow of rotating and twisting charged black holes with cloud of strings and quintessence,
Reference 60
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 8c7b9b80-8e82-43c1-b008-0ac9179de57d · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole 4D Einstein-Gauss-Bonnet black hole in Power-Yang-Mills field: a shadow study,
Reference 61
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 7a49f088-3a1f-449d-ab5c-e32a4893902b · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole A coordinate-independent characterization of a black hole shadow,
Reference 62
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation d02b640d-f490-4895-b59b-8cd38c381840 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Black Hole Parameter Estimation from Its Shadow,
Reference 63
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation fc97aad0-cf4a-4fd0-a821-bf641c66c701 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Analytical calculation of black hole spin using deformation of the shadow,
Reference 64
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 041ccca5-8e6a-4a1e-8518-aea06633e503 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole,
Reference 65
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 4ad5182a-5485-474b-89eb-3bc21af91e55 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole,
Reference 66
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation ba36949a-b520-43e5-ab10-1d2ae444c82b · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric,
Reference 67
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 68991ffa-fd5d-40e2-bead-e2933f5629d8 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Measurement of the spin of the M87 black hole from its observed twisted light,
Reference 68
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation c12261dd-e4b7-488d-ac2a-efc8c7c896d3 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole New black hole spin values for Sagittarius A* obtained with the outflow method,
Reference 69
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation a0bd9b9c-c2d4-4254-8deb-2be911cd1ae8 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole First Sagittarius A* Event Horizon Telescope Results. IV . Variability, Morphology, and Black Hole Mass,
Reference 70
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 5cf3b295-8582-413c-ae5f-6cb51fc1691c · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Black hole explosions,
Reference 71
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 8e16a749-c6d2-4663-829c-bd78c39590bf · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Deflection angle and shadow behaviors of quintessential black holes in arbitrary dimensions,
Reference 72
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 84d2ea6d-c7cb-4dea-b4ae-eb1587e3c585 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Observing the shadow of Einstein-Maxwell-Dilaton-Axion black hole,
Reference 73
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 938a1b38-2f35-44f6-a13e-89ea9ba04a14 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Fine structure of high-energy absorption cross sections for black holes,
Reference 74
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 9ea28959-24a8-48bf-8851-0be7a11305c6 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Shadow of a spinning black hole in an expanding universe,
Reference 75
Source-reported events for the cited work
Unavailable: canonical work link unavailable.
Observation 98001d3a-6d54-46cd-86ac-557283783b24 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole Vi`ete, descartes and the cubic equation,
Reference 76
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
Observation 63f2636a-e7ba-4d57-a774-c9b60a170a91 · outbound
Shadow of a nonlinear electromagnetic generalized Kerr-Newman-AdS black hole 92.34 the cubic equation – a new look at the irreducible case,
Reference 77
Source-reported events for the cited work
No event found in the named queried sources as of 2026-08-17T06:30:58.91139+00:00.
No inbound Pith citation observations are available.