1967 issue #1
1968 February
1968 March
1970 February
1970 March
1971 April
1971 August
1971 September
1971 October
1971 December
1972 February
1972 April
1972 July
1972 August
1972 September
1972 October
1972 November
1972 December
1973 January
1973 February
1973 March
1973 June
1973 July
1973 August
1973 September
1973 October
1973 December
1974 March
1974 June
1974 November
1975 January
1975 February
1975 March
1975 July
1975 September
1975 October
1975 December
1977 March
1977 April
1978 February
1978 June
1978 August
1978 September
1978 October
1979 January
1979 March
1979 May
1980 December
1981 January
more to come