1968
January January; 28 (1): 1 - 158	February February; 28 (2): 159 - 390	March March; 28 (3): 391 - 624
April April; 28 (4): 625 - 809	May May; 28 (5): 811 - 1005	June June; 28 (6): 1007 - 1215
July July; 28 (7): 1217 - 1461	August August; 28 (8): 1463 - 1663	September September; 28 (9): 1665 - 1921
October October; 28 (10): 1923 - 2175	November November; 28 (11): 2177 - 2400	December December; 28 (12): 2401 - 2572