Rodgers, Raymond
Alexander Hamiltion Institute, 1962
Buku Teks
Digby, Margaret
Hutchinson University Library , 1960
Buku Teks
Sayers, R.S.
Oxford University Press , 1967
Buku Teks
Rockefeller, David
McGraw-Hill , 1964
Buku Teks
Chew, David B. H.
Printers and Converters Ltd., 1973
Buku Teks