X. Luo and P. Niu, “Eigenvalues Problems for Square Sum Operators Consisting of Vector Fields,” Mathematica Applicata, Vol. 10, No. 4, 1997, pp. 101-104.

has been cited by the following article:

• TITLE: Riesz Means of Dirichlet Eigenvalues for the Sub-Laplace Operator on the Engel Group

  AUTHORS: Jingjing Xue

  KEYWORDS: Engel Group; Sub-Laplace Operator; Eigenvalues; Riesz Mean

  JOURNAL NAME: Advances in Pure Mathematics, Vol.3 No.9B, December 24, 2013

  ABSTRACT: In this paper, we are concerned with the Riesz means of Dirichlet eigenvalues for the sub-Laplace operator on the Engel group and deriver different inequalities for Riesz means. The Weyl-type estimates for means of eigenvalues are given.