Garland , 1993
Buku Teks
Ambrose, Stephen E., author
Yayasan Obor Indonesia, 2004
Buku Teks
Boorstin, Daniel J., author
Gadjah Mada University Press, 1990
Buku Teks
Washington U.S. Department of Health, Education, and Welfare 1955
Buku Teks
Artikel Jurnal