Amstrong, Michael
Crest Publishing House, 2002
Buku Teks
Henry, Anthony E., author
Oxford University press, 2011
Buku Teks
Cullen, John B. (John Brooks), 1948-, author
Thomson, 2005
Buku Teks
Dess, Gregory G., author
McGraw-Hill/Irwin, 2004
Buku Teks
Bush, Tony, author
IRCiSoD, , 2006
Buku Teks