NG 45-2 Mount Everest. Tile of the Map India and Pakistan 1:250,000. Series U502, U.S. Army Map Service, 1955
Cropping and annotation added by uploader as own work

The later stages of the route taken by the w:1975 British Mount Everest Southwest Face expedition as described in Bonington, Chris (1976)       Everest the Hard Way, London:  Hodder and Stoughton  ISBN:  0340208333. .
http://www.lib.utexas.edu/maps/ams/india/ng-45-02.jpg
U.S. Army Map Service