2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/157369We emphasize that there exist four Dirac-type points in the electron-energy spectrum of a graphite bilayer near the point K of its Brillouin zone. One of the Dirac points is at the point K, and three Dirac points lie nearby. Each of these three points generates the Berry phase $π$, while the Dirac point at K gives the phase $-π$. It is these four points that determine the Berry phase in the bilayer. If an electron orbit surrounds all these points, the Berry phase is equal to $2π$.4 pages, 2 figures, submitted to Phys. Rev. B ; expandedMaterials Sciencetext