18 - 22 May, 1975

25 - 29 April, 1976

21 - 25 November, 1976

20 - 24 February, 1977

22 - 30 May, 1977

06 - 09 November, 1977

23 - 26 April, 1978

19 - 22 November, 1978

22 - 25 April, 1979