Condliffe, Peter
Tape Publications, 1991
Buku Teks
edited by Anne Grodzins Lipow and Deborah A. Carver
American Library Association, 1992
Buku Teks SO
Betty, John Galtress, 1922-
McGraw-Hill, 1993
Buku Teks SO
Hogan, Rex, 1944-
Prentice-Hall, 1990
Buku Teks SO
Casey, Francis
Macmillan, 1985
Buku Referensi