▎ 摘　　要

We discuss the electron energy spectra and the Berry phases for graphene, a graphite bilayer, and bulk graphite, allowing for a small spin-orbit interaction. If an electron orbit in the Brillouin zone surrounds several Dirac points (band-contact lines in graphite), one can find the relative signs of the Berry phases generated by these points (lines) by taking this interaction into account. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2981389]