Blank, Steve, author
K & S Rench, Inc Publishers, 2012
Buku Teks
Siropolis, Nicholas C., author
Houghton Miffiln, 1977
Buku Teks
Tuchman, Robert, author
American Management Association;, 2009
eBooks
Green, Charles H., author
McGraw-Hill , 2012
Buku Teks
Johnson, Luke, author
Penguin book, 2013
Buku Teks