[publisher not identified], [date of publication no identified]
Buku Teks
Malinowski, Jon C.
McGraw-Hill, 2012
Buku Teks SO
Senior, Michael
Longman, 1979
Buku Teks SO
Lebon, J. H. G.
Hutchinson University Library, 1969
Buku Teks
Huntington, Ellsworth
John Wiley & Sons, 1951
Buku Teks SO