TY  - RPRT
TI  - Derivation of a general expression for the momentum matrix elements within the envelope-function approximation.
AU  - F Szmulowicz
PY  - 1995
DO  - 10.1103/physrevb.51.1613
UR  - https://pubmed.ncbi.nlm.nih.gov/9978880/
ID  - 9978880
ER  -