Artikel Jurnal
Lowell, Mildred Hawksworth, author
The Scarecrow Press, 1968
Buku Teks
Quesada, Robert, author
Pearson Prentice Hall, 2005
Buku Teks
Boss, Richard W., author
G.K. Hall Publishers, 1987
Buku Teks
Robertson, Deborah A., author
American Library Association, 2005
eBooks