edited by Barry Turner
Macmillan and Free Press, 1992
Buku Referensi
Maimon, Elaine P.
McGraw-Hill, 2003
Buku Referensi
Maimon, Elaine P.
McGraw-Hill, 2002
Buku Teks SO
McMahan, Elizabeth
McGraw-Hill, 1984
Buku Teks SO
edited by Jean M. Fredette
Writer`s Digest Books, 1988
Buku Teks SO