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