Smith, Huston, author
Harper & Brothers, 1955
Buku Teks
Mayhew, Lewis B., author
Jossey-Bass, 1973
Buku Teks
Gordon, Robert Aaron, author
Columbia University Press, 1959
Buku Teks
Dorodjatun Kuntjoro-Jakti, author
University of Indonesia, 2005
Buku Teks
edited by T. Marzuki Jacob
Universitas Sumatera Utara, 1994
Buku Referensi