Kirst-Ashman, Karen Kay, author
Thomson , 2006
Buku Teks
Morales, Armando, author
Allyn and Bacon, 1983
Buku Teks
Nabillah Ulfah, author
Fakultas Ilmu Sosial dan Ilmu Politik Universitas Indonesia, 2018
UI - Skripsi (Membership)
Prentice Hall of India, 1977
Buku Teks
Simons, Ronald L., author
Macmillan, 1985
Buku Teks