ARCO The 1st Name in College Guides
Macmillan General Reference, 1994
Buku Referensi
Gustafon, R. David, author
Thomson Brooks/Cole, 2007
Buku Teks
Giambattista, Alan., author
McGraw-Hill, 2007
Buku Teks
Coletta, Vincent, author
Mosby, 1995
Buku Teks
Kenworthy, Ray W., author
F.A. Davis, 1961
Buku Teks