Walker, E. Ronald, author
University of Chicago Press, 1947
Buku Teks
Harrod, R.F., author
Macmillan, 1956
Buku Teks
Seth, M.L., author
S. Chand, 1969
Buku Teks
edited by J.P. Nieuwenhuysen and P.J. Drake
Melbourne Unversity Press, 1977
Buku Teks
Tinbergen, Jan, 1903-, author
North-Holland Publishing , 1952
Buku Teks