N. Holloway, S. Ravindran, and A. Gibbons. Graph-Theoretic Concepts in Computer Science, volume 790 of Lecture Notes in Computer Science, Springer, Berlin / Heidelberg, (1994)
E. Anshelevich, and A. Karagiozova. Proceedings of the thirty-ninth annual ACM symposium on Theory of computing, page 391--400. New York, NY, USA, ACM, (2007)