Field, G. Lowell
Cornell University Press, 1967
Buku Teks
Strong, C.F.
Sidgwick & Jackson Limited, 1960
Buku Teks
Roucek, Joseph S.
Thomas Y. Crowell Company, 1950
Buku Teks
Strong, C.F.
Nuansa, 2004
Buku Teks
Chilcote, Ronald H.
Routledge, 2000
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