TY  - RPRT
TI  - A UNIFYING PRINCIPAL IN QUANTIFICATION THEORY.
AU  - R M Smullyan
PY  - 1963
DO  - 10.1073/pnas.49.6.828
UR  - https://pubmed.ncbi.nlm.nih.gov/16591106/
ID  - 16591106
ER  -