1. Garey M R, Johnson D S. Computers and Intractability: a Guide to the Thoery of NP-completeness. New York: Freeman, W. H. and Company, 1979
2. Roth-Korostensky C. Algorithms for building multiple sequence alignments and evolutionary trees. Dissertation for Doctoral Degree. ETH Zürich 13550, 2000
3. Stege U. Resolving conflicts from problems in computational biology. Dissertation for Doctoral Degree. ETH Zürich 13364, 2000
4. Hochbaum D. Approximating covering and packing problems: set cover, vertex cover, independent set, and related problems. In: Hochbaum D, ed. Approximation Algorithms for NP-Hard Problems. Boston: PWS Publishing Company, 1997. 94–143
5. Balasubramanian R, Fellows M R, Raman V. An improved fixed parameter algorithm for vertex cover. Inf Process Lett, 1998, 65: 163–168