Pirages, Dennis C.
Ark II : social response to environmental imperatives
The Viking Press, 1974
 Buku Teks
Fogel, Robert William
Railroads and American economic growth : essays in econometrics history
Johns Hopkins Press, 1964
 Buku Teks
Encyclopedia of American history : erlarged and update
edited by Richard B. Morris
Harper and Row , 1965
 Buku Referensi
Bailey, Thomas Andrew, 1902-1983
The American pageant : a history of the republic; Volume II
D.C. Heath, 1987
 Buku Referensi
The American family in social-historical/ Michael Gordon,(ed)
St.Martin's Press, 1983
 Buku Teks