Harrod, R.F.
Macmillan, 1956
Buku Teks
Seth, M.L.
S. Chand, 1969
Buku Teks
edited by J.P. Nieuwenhuysen and P.J. Drake
Melbourne Unversity Press, 1977
Buku Teks
Tinbergen, Jan, 1903-
North-Holland Publishing , 1952
Buku Teks
Hansen, Alvin Harvey, 1887-1975
McGraw-Hill, 1947
Buku Teks