Unsolved Problems in Group Theory. The Kourovka Notebook
  This is a collection of open problems in group theory proposed by hundreds of mathematicians from all over the world. It has been published every 2--4 years since 1965. This is the 20th edition, which contains 126 new problems and a number of comments on problems from the previous editions. 
E. I. Khukhro and V. D. Mazurov
math.GR