1. Worst-cast analysis of a new heuristic for the travelling salesman problem;Christofides,1976
2. Tight bounds for Christofides travelling salesman heuristic;Corneujols;Mathematical Programming,1978
3. Approximation algorithms for some postman problems;Frederickson;J. Assoc. Comput. Mach.,1979
4. Approximation algorithms for some routing problems;Frederickson;SIAM J. Comput.,1978
5. Worst-case analysis of algorithms for the travelling salesman problem;Frieze;Operations Res. Verfahren,1979