FitzGerald, Robert David, 1902-
University of Queensland Press, 1987
Buku Teks
Day, A. Grove (Arthur Grove), 1904-1994
Twayne, 1974
Buku Teks
Robert, D.S.
Harper & Row, 1981
Buku Teks
Chellis, Robert D
McGraw-Hill Company, 1961
Buku Teks
Cambridge University Press, 2008
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