J Exp Anal Behav. 1974 Mar;21(2):381-2. doi: 10.1901/jeab.1974.21-381.
Journal of the experimental analysis of behavior
J V Keller
PMID: 16811751 PMCID: PMC1333206 DOI: 10.1901/jeab.1974.21-381
[No abstract available.]