title: Reinforcing effects of d-amphetamine: influence of novel ratios on a progressive-ratio schedule.
authors.affiliation: aDepartments of Behavioral Science bPsychiatry cAnatomy and Neurobiology dPediatrics, College of Medicine ePsychology, College of Arts and Science, University of Kentucky, Lexington, Kentucky.
authors.forename: Rajkumar J
authors.initials: RJ
authors.lastname: Sevak
authors.forename: William W
authors.initials: WW
authors.lastname: Stoops
authors.forename: Paul E A
authors.initials: PE
authors.lastname: Glaser
authors.forename: Lon R
authors.initials: LR
authors.lastname: Hays
authors.forename: Craig R
authors.initials: CR
authors.lastname: Rush