Cohen, Bernard P.
Elsevier, 1975
Buku Teks SO
Simmers, Louise
Thomson , 2005
Buku Teks SO
Dawe, Renee A.
McGraw-Hill, 1995
Buku Teks SO
edited by G. N. Appell and Leigh R. Wright
Cornell University, 1978
Buku Referensi
Bayt, Phyllis Theiss
Glencoe Publishing Company, 1982
Buku Teks SO