Edwards, Mark
LID Publishing , cop, 2015
Buku Teks
Barry, Ann Marie Seward
State University of New York, 1997
Buku Teks
Artikel Jurnal
Angelakos, Diogenes J.,
McGraw-Hill, 1968
Buku Teks
Pelton, Joseph N., author
Mt.Airy, Maryland Lomond Books , 1974
Buku Teks