Gauwitz, Donna F, author
McGraw-Hill, Higher Education, 2005
Buku Teks
Bayt, Phyllis Theiss
Glencoe Publishing Company, 1982
Buku Teks
Humphries, Judith
Kogan Page, 1994
Buku Teks
Mathur, Hari Mohan, author
Sage, 1986
Buku Teks
Tulloch, Mitch, author
McGraw-Hill, 2000
Buku Referensi