1. Invariant imbedding and mathematical physics—I: Particle processes;Bellman;J. Math. Phys.,1960
2. Functional equations, wave propagation and invariant imbedding;Bellman;J. Math. Mech.,1959
3. Wave branching processes and invariant imbedding —I;Bellman,1961
4. Radiative Transfer;Chandrasekhar,1950
5. On the theory of age-dependent stochastic branching processes;Bellman,1948