Mishan, E. J., author
Routledge, 1972
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Stewart, Jr. Joseph T.
John Wiley & Sons, 1981
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Bookstaber, Richard M.
Probus publishing, 1990
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Epstein, Cynthia Fuchs, author
University of Califoenia Press , 1970
Buku Teks
University Toronto, 1977
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