Stebbins, Richard P.
Harper & Brothers, 1955
Buku Teks
Newman, Robert P.
Macmillan, 1961
Buku Teks
Humphrey, Don D., author
Frederick A. Praeger , 1962
Buku Teks
Schulz, Donald E.
Westview Press, 1994
Buku Teks
Meita Fitriani, author
2012
UI - Tesis (Open)