* Corne, D.; Dorigo, M. and Glover, F. (1999) - New Ideas in Optimization, McGraw-Hill
* Nemhauser , G. L. e Woley, L. A. (1999) - Integer and Combinatorial Optimization, Wiley Interscience Series in Discrete Mathematics and Optimization
* Cook, W.J., Cunningham, W. H. e William R. (1998) - Combinatorial Optimization, Pulleyblank and Alexander Schrijver, Wiley Interscience Series in Discrete Mathematics and Optimization