Tinbergen, Jan, 1903-, author
North-Holland Publishing , 1952
Buku Teks
Walker, E. Ronald, author
University of Chicago Press, 1947
Buku Teks
Cross, Rod
Martin Robertson , 1982
Buku Teks
Harrod, R.F., author
Macmillan, 1956
Buku Teks
Boulding, Kenneth E. (Kenneth Ewart), 1910-1993, author
Prentice-Hall, 1958
Buku Teks