1. Diffuse reflection of light by a foggy medium;Ambarzumian;Doklady Akad. Nauk SSSR,1943
2. On the principle of invariant imbedding and propagation through inhomogeneous media;Bellman,1956
3. On the principle of invariant imbedding and diffuse reflection from cylindrical regions;Bellman,1957
4. On the principle of invariant imbedding and one-dimensional neutron multiplication;Bellman,1957
5. On the principle of invariant imbedding and neutron transport theory-I: One-dimensional case;Bellman;J. Math. and Mech.,1958