Henry, David D
Jossey-Bass Publishers, 1975
Buku Teks
Barck,Oscar Theodore
Macmillan, 1950
Buku Teks
Barck, Oscar Theodore, Jr., 1902-1993, author
New York, N.Y. Macmullan c.1965,
Buku Teks
Russell, Bertrand, 1872-1970, author
George Allen and Unwin, 1957
Buku Teks
Nickersen, Jane Soames
The Devin-Adair Company, 1961
Buku Teks