Ryans, John K.
Ohio Kent State University Press , 1974
Buku Teks
Parker, Earl R.
McGraw-Hill, 1967
Buku Teks
Parker, Earl R.
McGraw-Hil Book Company, 1967
Buku Teks
Davis, H.W.C.
Oxford University Press, 1960
Buku Teks
Wolf, Eric R.
University of California Press, 1997
Buku Teks