Campbell, William Giles, author
Houghton Mifflin, 1967
Buku Teks
Oliver, Paul, editor
Sage, 2014
Buku Teks
Szuchman, Lenore T., author
Wadsworth, 2014
Buku Teks
Podis, Leonard A., author
Scott, foresman and Company3, 1983
Buku Referensi
Watson, George, author
Longman, 1987
Buku Teks