Graber, Doris A., author
Congressional Quarterly Press, 1980
Buku Teks
Abdul Razak, editor
AMIC, 2000
Buku Teks
Wilson, Stan Le Roy, author
McGraw-Hill, 1995
Buku Teks
Berrigan, Frances J., author
UNESCO, 1977
Buku Teks
Biagi, Shirley, author
Wadsworth and Cengage Learning, 2012
Buku Teks