TY  - RPRT
TI  - 'Endogenous' and 'exogenous': a useful dichotomy?
AU  - A Lewis
PY  - 1971
DO  - 10.1017/s0033291700041817
UR  - https://pubmed.ncbi.nlm.nih.gov/5148527/
ID  - 5148527
ER  -