Gutsche, Jeremy, 1978-, author
Crown Business, 2015
Buku Teks
Moody, Paul E.
McGraw-Hill, 1983
Buku Teks
Baskinger, Mark, author
Watson-Guptill Publications, 2013
Buku Referensi
Gonzalez, Ruben
Gramedia Pustaka Utama, 2008
Buku Teks
Mather, Peter, author
South Australia, 1984
Buku Teks