Steel, Robert George Douglas, 1917-
McGraw-Hill, 1960
Buku Teks
Akwasi Asabere-Ameyaw
Sense, 2012
eBooks
Gilliam, Ronald B.
Jones and Bartlett Publishers, 2011
Multimedia
Edited by McClung; Patricia A.
American Library Association, 1985
Buku Teks
Agnew, Neil McK.
Prentice-Hall, 1982
Buku Teks