Cummings, Michael R.
Brooks/Cole, Cengage Learning, 2011
Buku Teks
Montagu, Ashley, 1905-1999
Word Publishing, 1995
Buku Teks
Horwitz, Allan V.
Oxford University Press, 2016
eBooks
Tead, Diana
Educational, Scientific and Cultural Organization, 1952
Buku Teks
Jenkins, John B.
Harper-Collins, 1990
Buku Teks