Blackburn, Robert:

(1920-2003) African American lithographer who worked in Harlem as a young man and became one of the most influential in his field. In 1948, Blackburn opened his own workshop, which was open to any artist. The Creative Graphic Workshop was renamed the Printmaking Workshop and is still around today. In 1949 he was declared a master printer. His role as a printmaker has tremendous influence on the art world.
http://www.answers.com/topic/robert-blackburn-artist

Source: Patton, Sharon F. African-American Art. Oxford: Oxford University Press, 1998. 147.