RT Journal Article SR Electronic T1 Differential effects of delta-9-tetrahydrocannabinol and methanandamide on operant behavior in CB1 knockout and wild type mice JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics DO 10.1124/jpet.103.055376 A1 Cassandra Y Baskfield A1 Billy R Martin A1 Jenny L Wiley YR 2004 UL http://jpet.aspetjournals.org/content/early/2004/01/12/jpet.103.055376.abstract AB