Dopamine Blockade and Clinical Response: Evidence for Two Biological Subgroups of Schizophrenia. - Wolkin, Adam; Barouche, Faouzia; Wolf, Alfred P.; Rotrosen, John; Fowler, Joanna S.; Shiue, Chyng-Yann; Cooper, Thomas B.; Brodie, Jonathan D. (American Journal of Psychiatry, 1989)