edited by Peter M. Blau
Open Books, 1976
Buku Teks
Waldo, Dwight, author
Ronald Press, 1948
Buku Teks
Trautz, F.M.
Munchen Muller 1926
Buku Teks
Arasartnam, Sinnappah, author
Prentice-Hall, 1964
Buku Teks
Bailey, Sydney D., author
William Brendon ans Son, 1952
Buku Teks