1. On the principle of invariant imbedding and propagation through inhomogeneous media;Bellman,1956
2. Transport theory and invariant imbedding;Bellman,1959
3. On the principle of invariant imbedding and one-dimensional neutron multiplication;Bellman,1957
4. Invariant imbedding and neutron transport theory. II. Functional equations;Bellman;J. Math. and Mech.,1958
5. Finite atmospheres with isotropic scattering;Busbridge;Monthly Notices Roy. Astron. Soc.,1955