R. K. Ahuja, T. L. Magnanti, J. B. Orlin-desrochers, and F. Soumis, Network Flows : Theory, Algorithms, and Applications A generalized permanent labeling algorithm for the shortest path problem with time windows, Information Systems and Operations Research, vol.26, pp.191-212, 1988.

L. K. Fleischer, K. D. , W. Garey, and D. S. Johnson, Fast and simple approximation schemes for generalized flow, Proceedings of the 10th annual ACM-SIAM Symposium on Discrete Mathematics, 1999.
DOI : 10.1007/s101070100238