David Braun (July 13, 2010). "Nat Geo awards Alexander Graham Bell Medals to GIS pioneers". National Geographic Society. Archived from the original on December 24, 2011. Retrieved June 30, 2011.
"Bradford and Barbara Washburn ... received it in 1980 for their contributions to geography and cartography".
David Braun (July 13, 2010). "Nat Geo awards Alexander Graham Bell Medals to GIS pioneers". National Geographic Society. Archived from the original on December 24, 2011. Retrieved June 30, 2011.
"Bradford and Barbara Washburn ... received it in 1980 for their contributions to geography and cartography".