- Geological Survey (U.S.)
- Digital Commonwealth
- Boston Public Library
- The Survey
Surveyed in 1902-1903. Contour interval 50 feet." Relief also shown by spot heights. The Grand Canyon of the Colorado River by Francois E. Matthes"--Verso. U.S. Geological Survey ; E.M. Douglas, geographer in charge ; topography by Franc̜ois E. Matthes.
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