Staff. "Obituaries". University of Colorado. Archived from the original on 2010-06-04. Retrieved 2010-02-09. See entry for Leonard Lewin. Professor Emeritus Leonard Lewin 'established and, for many years, led study groups under the guidance of Idries Shah, Omar Ali-Shah and Arif Ali-Shah', according to his University of Colorado obituary.
Staff. "Obituaries". University of Colorado. Archived from the original on 2010-06-04. Retrieved 2010-02-09. See entry for Leonard Lewin. Professor Emeritus Leonard Lewin 'established and, for many years, led study groups under the guidance of Idries Shah, Omar Ali-Shah and Arif Ali-Shah', according to his University of Colorado obituary.