1. X. Xu, Representations of Lie Algebras and Partial Differential Equations, Springer, Singapore, 2017.

2. X. Xu, Algebraic Approaches to Partial Differential equations, Springer, Heidelberg/New York/Dordrecht/London, 2013.

3. X. Xu, Kac-Moody Algebras and Their Representations, China Science Press, 2007.

4.  X. Xu, Introduction to Vertex Operator Superalgebras and Ttheir Modules, Kluwer Academic Publishers, Dorecht/Boston/London, 1998.