Abigail Adams, John Adams, L. H. Butterfield, Marc Friedlaender, Mary-Jo Kline (1975). “The Book of Abigail and John: Selected Letters of the Adams Family, 1762-1784”, p.173, UPNE
Attributed to Margaret Mead in Michael S. Matthews, Ph.D. and Jaime A. Castellano, Ed.D. "Talent Development for English Language Learners: Identifying and Developing Potential", November 15, 2013.