Aspnes, David E. (1966). "Electric-Field Effects on Optical Absorption near Thresholds in Solids". Physical Review. 147 (2): 554–566. doi:10.1103/PhysRev.147.554. ISSN0031-899X.
Aspnes, David E. (1966). "Electric-Field Effects on Optical Absorption near Thresholds in Solids". Physical Review. 147 (2): 554–566. doi:10.1103/PhysRev.147.554. ISSN0031-899X.