NAGELS, P., TICHÝ, Ladislav, TICHÁ, H. Observation of variable-range hopping conduction in a Ge-Sb-S glass alloyed with CoS. Journal of Non-Crystalline Solids. 1993, 164-166(-), 1187-1190. ISSN 0022-3093. E-ISSN 1873-4812.