1Barnouw, Erik, International Encyclopedia of Communication, New York: Oxford University Press, 1989, 4 Vols. PP. 147 - 189.
2Blanchard, Margaret A. , History of the Mass Media in the United States: An Encyclopedia, Chicago: Fizroy Dearborn, 1998,PP698 - 756.
3Canyons of the Colorado ( Flood & Vincent, 1895. reprint, Dover Publications, Inc., 1961, retifled The Exploration of the Colorado River and its Canyons ) .
4Bill Steinbacher- Kemp, "John Wesley Powell", from the web, www. lib. niu. edu/ipo/2001/ilfa0107, html - 33k
5Gifford Pinchot, Breaking New Ground, Washirtgton, D. C. : Island Press, 1998, P 505.
6"Stephen Tyng Mather, Cornelius Amory Pugsley Gold Medal Award, 1928 " from the web site : rpts. tamu. edu/pugsley/mather. html
7Foresto, RA. , American's national parks and their keepers. Washington D. C. : Resources for the Future. 1984, PP16 -24.
8"Papers of Irving Brant, ( 1885 - 1976 )", from the web : lib. uiowa, edu/spee - coll/MSC,/ToMsC600/MsC569/brant, html
9Jim Brett, " Rosalie Barrow Edge " from the web: depweb, state, pa. us/heritage/cwp.
10Michael Frome, "The Roots of e-journalism", SEJournal, Spring 2004, P16.
