TY  - RPRT
TI  - Choice between fixed-interval schedules: Graded versus step-like choice functions.
AU  - R L Shull
PY  - 1992
DO  - 10.1901/jeab.1992.58-37
UR  - https://pubmed.ncbi.nlm.nih.gov/16812665/
ID  - 16812665
ER  -