Charles Callahan

Effects of overtraining on verbal discrimination shifts: A differentiation-suppression hypothesis

C. Paul, Charles Callahan, 1972 .

Transfer-activated response sets: Effect of overtraining and percentage of items shifted on a verbal discrimination shift

C. Paul, Charles Callahan, Marilyn Mereness, 1968 .

Cocaine Exposure During Pregnancy: Improving Assessment With Radioimmunoassay of Maternal Hair

H. Barr, Z. Brown, T. Grant, 1994, Obstetrics and gynecology.