"Becoming a Great School: Harnessing the Powers of Quality Management and Collaborative Leadership". Book by Dr. Kenneth B. Cooper, Nels Gustafson and Joseph G. Salah (p. 9), December 24, 2013.
Albert Einstein (2000). “Albert Einstein in his own words in two complete books: Relativity-the special and general theory; Out of my later years-the scientist, philosopher and man portrayed through his own words”