1. and , Random evolutions, Markov chains, and systems of partial differential equations, Proc. Nat. Acad. Sci., February 1969.
2. and , Theory of random evolutions with applications to partial differential equations, Trans. Amer. Math. Soc., May, 1971, pp. 405–418.
3. Differential equations with a small parameter and the central limit theorem for functions defined on a finite Markov chain
4. Explicit solution of a class of higher order Cauchy problems, J. of Differential Equations, November, 1970, pp. 570–579.