Discussiones Mathematicae Graph Theory 32(2) (2012)
255-261

doi: 10.7151/dmgt.1612

Li Su, Hong-Hai Li and Liu-Rong Zheng
College of Mathematics and Information Science |

**Keywords:** digraph, Laplacian matrix, eigenvalue, wheel

**2010 Mathematics Subject Classification:** 05C50, 15A18.

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Received 10 February 2011

Revised 10 May 2011

Accepted 10 May 2011