McLaughlin, Andrew C.
Appleton Century Crofts, 1935
Buku Teks
Swisher, Carl Brent
University of Chicago Press, 1946
Buku Teks
Hockett, Homer Carey
Macmillan, 1939
Buku Teks SO
Myers, Gustavus
Random House, 1943
Buku Teks
Risjord, Norman K.
Prentice-Hall, 1985
Buku Teks SO