Bicyclic graphs with exactly two main signless Laplacian eigenvalues
  A signless Laplacian eigenvalue of a graph $G$ is called a main signless Laplacian eigenvalue if it has an eigenvector the sum of whose entries is not equal to zero. In this paper, all connected bicyclic graphs with exactly two main eigenvalues are determined. 
He Huang and Hanyuan Deng
math.CO