Cross, Rod
Martin Robertson, 1982
Buku Teks
Krugman, Paul R.
Addison-Wesley , 1997
Buku Teks
Tinbergen, Jan, 1903-
North-Holland Publishing , 1952
Buku Teks
Walker, E. Ronald
University of Chicago Press, 1947
Buku Teks
Meier, Gerald M.
Wiley, 1966
Buku Teks