Unesco , 1968
Buku Teks SO
Faludi, Andreas
Pergamon Press, 1978
Buku Teks
Beeby, C.E.
New Zealand Council for Educational Research, 1979
Buku Teks SO
Kaufman, Roger A.
Prentice-Hall, 1972
Buku Teks SO
Jackman, Hilda L.
Wadsworth and Cengage Learning, 2012
Buku Teks SO