Source, in full
On being told that a piece of work he thought was his discovery had duplicated an earlier mathematician's work. Quoted in "Pity the Scientist Who Discovers the Discovered" by Gina Kolata, New York Times: Week in Review (2006-02-05)
Attribution
Quote text and notes from Wikiquote: Lawrence Shepp (page history), available under CC BY-SA 4.0. Source quality and labels are our own summary of what Wikiquote records.