Distribution des nombres ℬ -libres dans de petits intervalles Jie Wu (1993) Journal de théorie des nombres de Bordeaux
Distribution of values of Euler's function over integers free of large prime factors A. Smati, J. Wu (1996) Acta Arithmetica
Divisibility of the κ-fold iterated divisor function of n into n Claudia Spiro-Silverman (1994) Acta Arithmetica