Levine, Donald N.
University of Chicago Press, 1974
Buku Teks
Penguin Books , 1970
Buku Teks
Richardson, W. Norman, author
Macmillan, 1976
Buku Teks
Michael, Donald N.
Jossey-Bass, 1985
Buku Teks
Wilber, Donald N.
Princeton University Press, 1955
Buku Teks