End of Muhammad's Life and the Beginnings of Islam, page 248, UniversityofPennsylvania Press, 2011. Alford T. Welch; Ahmad S. Moussalli; Gordon D. Newby
Active (GRASP) Ile-ẹkọ giga ti UniversityofPennsylvania (1989-1991). O jẹ ẹlẹgbẹ ti Association fun Ẹrọ Iṣiro, Institute of Electrical and Electronics Engineers
iwadii postdoctoral ati ni ọdun 1969, o kuro ni UI lati darapọ mọ UniversityofPennsylvania gẹgẹbi ẹlẹgbẹ iwadii postdoctoral ni Johnson Research Foundation