1. Almeida, A.M.de, P.C. Martins, and M. Souza, “Min-Degree Constrained Minimum Spanning Tree Problem: Complexity, properties, and formulations”, Working Paper 6 (2006), Center for Operational Research of the University of Lisbon
2. Computers and intractability: A guide to the theory of NP-completeness;Garey,1979
3. A greedy heuristic for a minimum-weight forest problem;Imielińska;Operations Research Letters,1993
4. Transitions in geometric minimum spanning trees;Monma;Discrete Computational Geometry,1992
5. Computational Complexity;Papadimitriou,1994