Păpară, Nicolae. “ On the Dynamic Programming Principle for Optimal Control Problems”. Rev. Anal. Numér. Théor. Approx. 27, no. 2 (August 1, 1998): 315–320. Accessed April 17, 2025. https://ictp.acad.ro/jnaat/journal/article/view/1998-vol27-no2-art12.