Buku Teks
Ellis, Ulrich, author
Melbourne University Press, 1963
Buku Teks
edited by Marc-David L. Seidel, Henrich R. Greve
Emerald, 2017
eBooks
Ranney, Austin, author
Harcourt, Brace and Company, 1956
Buku Teks
Hrebenar, Ronald J
Westview Press, 1986
Buku Teks