Brash, Donald T.
Australian National University , 1966
Buku Teks
Nwogugu, E.I.
Manchester University Press , 1965
Buku Teks
Schwabach, Robert.
Osborne McGraw-Hill , 1994
Buku Teks
Fulda, Carl H., author
Foundation Press, 1970
Buku Teks
Indonesian Embassy, 1967
Buku Teks