Hutchinson, Harry D., author
Appleton-Century-Crofts, 1967
Buku Teks
Hutchinson, Harry D., author
Meredith Corporation, 1971
Buku Teks
Currie, Lauchlin, author
Russell and Russell, 1968
Buku Teks
Anderson, Martin, author
Hover Institution Press, 1978
Buku Teks
Mints, Lloyd W., author
University of Chicago Press, 1956
Buku Teks