Complexity and Approximation
Combinatorial optimization problems and their approximability properties: by G. Ausiello, P. Crescenzi, G. Gambosi, V. Kann, A. Marchetti-Spaccamela, M. Protasi (Springer, 1999). Table of contents, errata, software supplement and a continuously updated catalog of approximability results.
Computational Complexity
(Birkhäuser) Tables of contents from vol.7 (1998) on. Full text to subscribers via LINK.
Hypertext Bibliography of Measures of Complexity
Bruce Edmonds; Manchester Metropolitan University.