On ${\cal N}_c$-Covering Groups of a Nilpotent Product of Cyclic Groups
  The first author, in 2001, presented a structure for the Baer-invariant of a nilpotent product of cyclic groups with respect to the variety of nilpotent groups. In this paper, using the above structure, we prove the existence of an ${\cal N}_c$-covering group for a nilpotent product of a family of cyclic groups. We also present a structure for the ${\cal N}_c$-covering group. 
Behrooz Mashayekhy and Ashraf Khaksar
math.GR