Aerial photo of Tuckerman Ravine with the headwall buried under snow in winter and Washington Observatory visible on the summit top right, from undated USFS monograph: AVALANCHE TERRAIN AND CONDITIONS IN THE PRESIDENTIAL RANGE, NEW HAMPSHIRE, US;
Kai-Uwe Allen, Snow Ranger, US Forest Service, White Mountain National Forest, New Hampshire, citing statistics and other sources from 1999, 2000, and earlier.
Kai-Uwe Allen, USFS Snow Ranger
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