1. R. Bellman,Dynamic Programming, Princeton University Press, Princeton, New Jersey, 1957.
2. R. Bellman, “On a quasi-linear equation,” Canadian J. Math., vol. 8, 1956, pp. 198–202.
3. R. Bellman, “A Markovian decision process,“ J. Math. and Mech., vol. 6, 1957, pp. 679–684.
4. R. Howard,Discrete Dynamic Programming, John Wiley and Sons, New York, 1960.
5. Exercise;G. Pólya,1945