TY  - RPRT
TI  - On Functions Whose Derivatives Do Not Vanish in a Given Interval.
AU  - G Polya
PY  - 1941
DO  - 10.1073/pnas.27.4.216
UR  - https://pubmed.ncbi.nlm.nih.gov/16578010/
ID  - 16578010
ER  -