Effects of caffeine and its metabolite paraxanthine on intracranial self-stimulation in male rats
Experimental and Clinical Psychopharmacology (2015) - Comments
pubmed: 25844631  doi: 10.1037/pha0000012  issn: 1936-2293  issn: 1064-1297 

Matthew F. Lazenka, F. Gerard Moeller, S. Stevens Negus