by Amilcar O. Herrera ... [et al.]
International Development Research Centre, 1976
Buku Teks SO
edited by Heraldo Munoz and Joseph S. Tulchin
Westview Press, 1984
Buku Teks SO
David B. Guralnik, editor in chief
Prentice-Hall, 1986
Buku Referensi
Victoria Neufeldt, David B. Guralnik, editor
Webster's New World, 1988
Buku Referensi
David B. Guralnik, editor in chief
William Collins Publishers, 1976
Buku Referensi