Comment on "Analytic model of the energy spectrum of a graphene quantum dot in a perpendicular magnetic field"

In recent work by Schnez et al. [PRB 78, 195427 (2008)], they studied the analytical model of the energy spectrum of a graphene quantum dot in a perpendicular magnetic field. In this comment we first point out that the results Eqs.(5), (6) and (11) presented by them in [1] are not reliable and then give our results.