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

Vol 1 No 7 – December 1957

Vol 2 No 8 – December 1955 (incomplete)

Vol 9 No 5 – August 1959

Missing Editions
Volume 1 No 1 (1951) to Volume 2 No 7, and

Volume 2 No 9 to Vol 9 No 4 (1959)