“Albert Schweitzer, Etching by Arthur William Heintzelman” by The Library od Congress Prints & Photographs Online Catalog; http://www.loc.gov/rr/print/catalog.html. Licensed under Public Domain via Wikimedia Commons – https://commons.wikimedia.org/wiki/File:AlbertSchweitzer,EtchingbyArthurWilliamHeintzelman.jpg#/media/File:AlbertSchweitzer,EtchingbyArthurWilliamHeintzelman.jpg