Neumann, Frank Algorithms and Complexity, MPI for Informatics, Max Planck Society;
http://eccc.hpi-web.de/report/2006/143/ (Any fulltext)
Neumann, F., & Witt, C. (2006). Ant Colony Optimization and the Minimum Spanning Tree Problem. Electronic Colloquium on Computational Complexity (ECCC): Report Series, 143, 1-12.