Israel, Saul
World geography today
Holt, Rinehart and Winston, 1976
Buku Teks SO
Federico, Ronald C.
Social welfare today's world
McGraw-Hill, 1990
Buku Teks
Management in the world today
edited by Don Hellriegel and John W. Slocum
Addison- Wesley , 1975
Buku Teks
Talbot
South Asia In The World Today
Buku Teks
Berger, Morroe
The Arab world today
Anchor Books, 1964
Buku Teks SO