1991
January January; 56 (1): 3 - 72	February February; 56 (2): 75 - 144	March March; 56 (3): 147 - 216
April April; 56 (4): 219 - 288	May May; 56 (5): 291 - 360	June June; 56 (6): 363 - 432
July July; 57 (1): 3 - 80	August August; 57 (2): 84 - 131	September September; 57 (3): 147 - 208
October October; 57 (4): 211 - 280	November November; 57 (5): 283 - 352	December December; 57 (6): 355 - 420