Sky and Telescope. 1971 vol.42 N 4,5,6 Ì|Ô: 1972 v.43 N 1,2,3,4,5,6 v.44 N 1,2,3,4,5,6 1973 v.45 N 3,4 v.46 N 1,2,3,4,5,6 1974 v.47 N 1,2,3,4,5,6 v.48 N 1,2,3,4,5,6 1975 v.49 N 1,2,3,4,5,6 v.50 N 1,2,3,4,5,6