Seth, M.L.
S. Chand, 1969
Buku Teks
edited by J.P. Nieuwenhuysen and P.J. Drake
Melbourne Unversity Press, 1977
Buku Teks
Walker, E. Ronald
University of Chicago Press, 1947
Buku Teks
Hansen, Alvin Harvey, 1887-1975
McGraw-Hill, 1947
Buku Teks
Harrod, R.F.
Macmillan, 1956
Buku Teks