1981
January January; 19 (1): 1 - 208	February February; 19 (2): 209 - 370	March March; 19 (3): 371 - 493
April April; 19 (4): 495 - 685	May May; 19 (5): 687 - 940	June June; 19 (6): 941 - 1091
July July; 20 (1): 1 - 149	August August; 20 (2): 151 - 279	September September; 20 (3): 281 - 423
October October; 20 (4): 425 - 562	November November; 20 (5): 563 - 704	December December; 20 (6): 705 - 853