Wiarda, Howard J., author
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Buku Teks
by Amilcar O. Herrera ... [et al.]
International Development Research Centre, 1976
Buku Teks
Westview Press , 1984
Buku Teks
David B. Guralnik, editor in chief
Prentice-Hall, 1986
Buku Referensi
Victoria Neufeldt, David B. Guralnik, editor
Webster's New World, 1988
Buku Referensi