1. The Traveling Salesman Problem. A Guided Tour of Combinatorial Optimization, Lawler, E.L., Lenstra, J.K., Rinnoy Kan, A.H.G., and Shmoys, D.B., Eds., New Yprk: Wiley, 1985.
2. Melamed, I.I., Sergeev, S.I., and Sigal, I.Kh., The Traveling Salesman Problem. I-III, Autom. Remote Control, 1989, no. 9, part 1, pp. 1147–1174; no. 10. part 1, pp. 1303–1325; no. 11, part 1, pp. 1459–1480.
3. The Traveling Salesman Problem and Its Variations, Gutin, G. and Punnen, A.P., Eds., Dordrecht, London: Kluwer, 2002.
4. Krotov, V.F., Approximate Synthesis of Optimal Control, Autom. Remote Control, 1964, vol. 25, no. 11, pp. 1369–1375.
5. Krotov, V.F. and Gurman, V.I., Metody i zadachi optimal’nogo upravleniya (Optimal Control Methods and Problems), Moscow: Nauka, 1973, pp. 265–271.