1. Invariant imbedding and wave propagation in stochastic media;Bellman,1960
2. “Invariant Imbedding” and Wave Propagation in Inhomogeneous Media;MacCallum;Sandia Corporation Research Report SC-4669(RR),1961
3. On the relation of transmission-line theory to scattering and transfer;Redheffer;J. Math. Phys.,1962
4. An Introduction to Transport Theory;Wing,1962
5. On the fundamental equations of invariant imbedding, I;Bellman,1961