1980
January January; 50 (1): 1 - 217	February February; 50 (2): 219 - 419	March March; 50 (3): 421 - 633
April April; 50 (4): 635 - 809	May May; 50 (5): 811 - 982	June June; 50 (6): 983 - 1167
July July; 51 (1): 1 - 200	August August; 51 (2): 201 - 422	September September; 51 (3): 423 - 684
October October; 51 (4): 685 - 955	November November; 51 (5): 957 - 1221	December December; 51 (6): 1223 - 1500