Validation of subgradient optimizationMichael HeldPhilip Wolfeet al.1974Mathematical ProgrammingPaper
The traveling-salesman problem and minimum spanning trees: Part IIMichael HeldRichard M. Karp1971Mathematical ProgrammingPaper
A dynamic programming approach to sequencing problemsMichael HeldRichard M. Karp1961ACM National Meeting 1961Conference paper