Here are the links to the Groundsheets published in the 1950s.

Vol 1 No 1 – July 1950

Vol 1 No 2 – October 1950

Vol 1 No 3 – November 1950

Vol 1 No 4 – December 1950

Vol 2 No 1 – February 1952

Vol 2 No 2 – April 1952

Vol 2 No 1 – February 1952

Vol 3 No 1 – February 1954

Vol 3 No 2 – March 1954

Vol 3 No 3 – April 1954

Vol 3 No 4 – May 1954

Vol 3 No 5 – August 1954

Vol 3 No 6 – September 1954

Vol 3 No 8 – December 1954

Vol 4 No 1 – February 1955

Vol 4 No 2 – March 1955

Vol 2 No 8 – December 1955 (incomplete)

Vol 1 No 7 – December 1957

Vol 9 No 5 – August 1959

Missing Editions
All 1951, 1953 1956 & 1958 editions, and
Volume 3 No 7 – 1954,
Volume 7 Nos 2 to 6 – 1957
Volume 9 Nos 1 to 4 & 6 to 8 – 1959