1. , and , A group of exponent 4 with derived length at least 4, Proc. Amer. Math. Soc. (39) 1973, pp. 228–233.
2. , and , Construction of a non-solvable group of exponent 5, pages 39–66 in Word Problems (edited by , and ), North-Holland, Amsterdam, 1973.
3. and , Lecture Notex, in preparation.