Berozashvili Y.N. , Keldysh L.V. , Bagaev V.S. , Belousova T.Y. Anisotropy of the Absorption of Polarized Light for Semiconductors in a Strong External Electric Field. IX Intern. Conf. on the Phys. of Semiconductors. Moscow.July 23-29 1968. Proc. , с. P.127 Shotov A.P. , Berozashvili Y.N. , Keldysh L.V. , Vul B.M. , Zavaritskaya E.I. , Bagaev V.S. About the energy spectrum of the heavily doped GaAs (Об энергетическом спектре сильно легированного арсенида галлия) / Ed.Dunod. Radiative recombination. Simpos. 7-th Intern. Conf. on Physics of Semiconductors, Paris, 1964 , с. P.149-154