Perlman, Richard, author
Dryden Press, 1972
Buku Teks
Ferguson, C. E., author
Richard D. Irwin, 1966
Buku Teks
Commons, John R.
Macmillan, 1956
Buku Teks
Walker, E. Ronald, author
University of Chicago Press, 1947
Buku Teks
Seth, M.L., author
S. Chand, 1969
Buku Teks