On extremal multiplicative Zagreb indices of trees with given number of   vertices of maximum degree
  The first multiplicative Zagreb index of a graph $G$ is the product of the square of every vertex degree, while the second multiplicative Zagreb index is the product of the products of degrees of pairs of adjacent vertices. In this paper, we explore the trees in terms of given number of vertices of maximum degree. The maximum and minimum values of $\prod_1(G) $ and $\prod_2(G) $ of trees with arbitrary number of maximum degree are provided. In addition, the corresponding extremal graphs are characterized. 
Shaohui Wang, Chunxiang Wang, Lin Chen, Jia-Bao Liu
math.CO