Langer, Susanne K., author
John Hopkins Press, 1964
Buku Teks
Mulvaney, Robert J., author
Essex Pearson, 2014
Buku Teks
editor, James A. Gould
Charles E. Merrill , 1971
Buku Teks
Pojman, Louis P., author
Thomson Wadsworth, 2006
Buku Teks
Cornman, James W., author
Macmillan, 1968
Buku Teks