Käte Traumann Steinitz (August 2, 1889-April 7, 1975) was a German-American artist, photographer, collector, writer, librarian, and expert on Leonardo da Vinci.
Biography on Wikipedia: https://en.wikipedia.org/wiki/Kate_Steinitz
Young Girl by Käte Steinitz / 1939 / Watercolor and chalk / Sheet: 17-1/2″x12-1/2″
UCLA Grunwald Center for the Graphic Arts at the Hammer Museum, Los Angeles, CA
Käte Steinitz on Artnet: http://www.artnet.com/artists/k%C3%A4te-steinitz/