TY  - RPRT
TI  - Dose and physical dependence as factors in the self-administration of morphine by rats.
AU  - J R Weeks
AU  - R J Collins
PY  - 1979
DO  - 10.1007/bf00433045
UR  - https://pubmed.ncbi.nlm.nih.gov/117486/
ID  - 117486
ER  -