Coe, Rodney M.
McGraw-Hill, 1970
Buku Teks SO
Stefanus Y. Setiawan
Fakultas Ilmu Komputer Universitas Indonesia, 2001
UI - Tesis Membership
Fowler, W.S
Nelson, 1976
Buku Teks SO
Artikel Jurnal
Wilbur, Sibyl
Christian Science Publishing Society, 1941
Buku Teks SO