Carritt, E.F.
Clarendon Press, 1935
Buku Teks SO
Adian Husaini
Dea Press, 2000
Buku Teks SO
Ahmad Suhelmi
Teraju Refleksi Masyarakat Baru, 2002
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Ray, James Lee
Houghton Mifflin, 1987
Buku Teks SO
Kaarbo, Juliet
Wadsworth, Cengage Learning, 2011
Buku Teks SO