Artikel Jurnal
Landsberg, Hans H., author
The Johns Hopkins Press , 1963
Buku Teks
edited by Samantha Schmehl Hines, Kathryn Moore Crowe
Emerald, 2017
eBooks
edited by Bill Cope
Chandos Publishing, 2006
Buku Teks
edited by Rae A. Earnshaw, John Vince
Springer, 2008
Buku Teks