1991
January January; 72 (1): 1 - 242	February February; 72 (2): 245 - 518	March March; 72 (3): 523 - 732
April April; 72 (4): 735 - 955	May May; 72 (5): 957 - 1173	June June; 72 (6): 1175 - 1409
July July; 73 (1): 1 - 217	August August; 73 (2): 221 - 455	September September; 73 (3): 461 - 686
October October; 73 (4): 691 - 921	November November; 73 (5): 925 - 1152	December December; 73 (6): 1153 - 1381