Approximation Algorithms for NP-hard Problems by Dorit Hochbaum |
Computers and Intractability: A Guide to the Theory of NP-Completeness by M. R. Garey and D. S. Johnson |
Handbook of Approximation Algorithms and Metaheuristics by T. Gonzalez |

Complexity and Approximation: Combinatorial Optimization Problems and Their Approximability Properties by G. Ausiello and P. Crescenzi and G. Gambosi and V. Kann and |
Approximation Algorithms by V. Vazirani |
Graph Algorithms, 2nd Edition by Shimon Even and Guy Even |

Graphs, Algorithms, and Optimization, Second Edition by William Kocay and Donald L. Kreher |
Algorithms in Java, Part 5: Graph Algorithms (3rd Edition) (Pt.5) by Robert Sedgewick |
Graphs, Networks and Algorithms by Dieter Jungnickel |

Algorithms in C, Part 5: Graph Algorithms (3rd Edition) (Pt.5) by Robert Sedgewick |