Letter to Arnold Carl Klebs, December 24, 1903
Letter to Arnold Carl Klebs, January 15, 1904
Letter to Arnold Carl Klebs, March 8, 1904
Letter to Arnold Carl Klebs, November 23, 1904
Letter to Arnold Carl Klebs, January 21, 1904
Letter to Arnold Carl Klebs, February 18, 1904
Letter to Arnold Carl Klebs, November 23, 1904
Letter to Arnold Carl Klebs, April 3, 1905
Letter to Arnold Carl Klebs, February 23, 1906
Letter to Arnold Carl Klebs, March 27, 1906