Elshafei, A. (1969). General Purpose Systems Simulator (GPSS). The Institute of National Planning.
Lua i Stíl Chicago (17ú heag.)Elshafei, Alwalid. General Purpose Systems Simulator (GPSS). Cairo: The Institute of National Planning, 1969.
Lua MLA (9ú heag.)Elshafei, Alwalid. General Purpose Systems Simulator (GPSS). The Institute of National Planning, 1969.