Buchman, Joseph
Englewood Cliffs, NJ, Prentice-Hall
Buku Teks
Shuchman, Abe
Holt, Rinehart and Winston, Inc., 1963
Buku Teks
Cooke, Steve
Prentice-Hall, 1991
Buku Teks
Taylor, Frederick Winslow
Harper & Brothers, 1947
Buku Teks
McFarlan, Franklin Warren
Macmillan, 1970
Buku Teks