Mahatma Gandhi (1965). “Glorious Thoughts of Gandhi: Being a Treasury of about Ten Thousand Valuable and Inspiring Thougths of Mahatma Gandhi, Classified Under Four Hundred Subjects”
"Letters of Friendship and Acquaintance" [Briefe der Freundschaft und Begegnungen] edited by Hans Kollwitz, p. 95; cited in "Käthe Kollwitz: Woman and Artist" by Martha Kearns, (p. 172), 1976.