Dingus, Lowell, author
Carlton, 2012
Buku Referensi
Braidwood, Robert J., author
Natural History Museum, 1963
Buku Teks
Braidwood, Robert J., author
Chicago Natural History Museum, 1951
Buku Teks
Murphy, Tom, author
American Management Association, 2007
eBooks
Hales, Dianne, author
Simon & Schuster, 2014
Buku Teks