Aplied Mathematics and Modeling ...............
Buku Teks
Ferris, Brian
World problems
Hulton Educational Publications, 1973
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Kornblum, William
Social problems
Prentice-Hall, 1992
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Russell, Bertrand, 1872-1970
The problems of philosophy
Oxford University Press, 1912
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Henslin, James M.
Social problems
McGraw-Hill, 1983
Buku Teks