Eli (A.L.) Levin received a Ph.D. degree in mathematics from Moscow State University in 1970. In 1979 he joined the Faculty of the Open University of Israel in Tel Aviv, where he is currently Associate Professor. Doron S. Lubinsky received a Ph.D. degree from Witwatersrand University, Johannesburg, South Africa, in 1981. In 1989 he joined the faculty of Witwatersrand University where he is currently Full Professor.