Here's an early intro from Bellman himself: https://www.ams.org/journals/bull/1954-60-06/S0002-9904-1954-09848-8/S0002-9904-1954-09848-8.pdf https://www.ams.org

Here's an early intro from Bellman himself: https://www.ams.org/journals/bull/1954-60-06/S0002-9904-1954-09848-8/S0002-9904-1954-09848-8.pdf https://www.ams.org/journals/bull/1954-60-06/S0002-9904-1954... It gets into continuous problems from section 6 on.