1. Angel, E., A. Jain, and R. Kalaba, “Initial-Value Problems in Potential Theory,” University of Southern California TR-70–22, April 1970.
2. Atkinson, F., “Wave Propagation and the Bremmer Series,” J. Math. Anal. and Appl. 1, 255–276, I960.
3. Bellman, R., and R. Kalaba, “Functional Equations, Wave Propagation, and Invariant Imbedding,” J. of Math. and Mechanics, 8, 683–704, 1959.
4. Bellman, R., and R. Kalaba, “Invariant Imbedding and Wave Propagation in Stochastic Media, “Electromagnetic Wave Propagation, “Academic Press, New York, pp. 243–252, 1960.
5. Bellman, R., and R. Kalaba, “Wave Branching Processes and Invariant Imbedding, I,” Proc. Nat. Acad. Sci., 47, 1507–1509, 1961.