DEVELOPMENT AND EVALUATION OF A MIXED-ANTIGEN ELISA FOR SERODIAGNOSIS OF ACTINOBACILLUS-PLEUROPNEUMONIAE SEROTYPES 1, 5, AND 7 INFECTIONS IN COMMERCIAL SWINE HERDS - BOSSE, JT; FRIENDSHIP, R; ROSENDAL, S; FENWICK, BW (JOURNAL OF VETERINARY DIAGNOSTIC INVESTIGATION, 1993)