December 1970

January-February 1971

15 February 1980

15 April 1980

15 May 1980

30 May 1980

15 June 1980

4 July 1980

15 July 1980

30 July 1980

12 August 1980

15 September 1980

30 September 1980

15 October 1980

30 October 1980

15 November 1980

30 November 1980

15 December 1980

15 January 1981

30 January 1981

13 February 1981

27 February 1981

13 March 1981

30 March 1981

16 April 1981

30 April 1981

15 May 1981

29 May 1981

15 June 1981

4 July 1981

15 July 1981

30 July 1981

14 August 1981

28 August 1981

15 September 1981

30 September 1981

15 October 1981

30 October 1981

16 November 1981

April 1982 

30 November 1982 

15 February 1983

15 April 1983

27 May 1983

29 July 1983

15 June 1984

(p. 1-2 only)

15 October 1984

(p. 1-2 only)

30 April 1985

(p. 11-12 only)