Here are the links to the Groundsheets published in the 1960s

Vol 10 No 2 – March 1960

Vol 11 No 3 – April 1961

Vol 11 No 6 – December 1961

Vol 12 No 3 – May 1962

Vol 12 No 6 – December 1962

Vol 13 No 5 – February 1964

Vol 14 No 2 – November 1964

Vol 14 No 4 – January 1965

Vol 15 No 3 – April 1966 (Pages 3 to 6)

Vol 16 No 5 – February 1967

Vol 16 No 6 – March 1967

Vol 16 No 7 – April 1967

Vol 16 No 11 – Nov-Dec 1967

Vol 17 No 3 – March 1968

Vol 17 No 4 – April 1968

Vol 17 No 6 – October 1968

Vol 17 No 7 – November 1968

Vol 17 No 8 – December 1968

Vol 18 No 1 – February 1969

Vol 18 No 2 – May 1969

Vol 18 No 5 – December 1969

Missing Editions
Volume 10 Nos 1, 3 to 6
Volume 11 Nos 1, 2, 4 & 5
Volume 12 Nos 1,2, 4 & 5
Volume 13 Nos 1,2,4, & 5
Volume 14 Nos 1 & 3
Volume 15  Nos 1, 2 & 3 (complete version)
Volume 16 Nos 1, 2, 3, 4, 8, 9, & 10
Volume 17 Nos 1, 2 & 5
Volume 18 No 3