1. A note on the convergence of semigroups of operators;Hasegawa,1964
2. Convergence of operator semigroups with applications to Markov processes;Kurtz;Stanford Dissertation,1967
3. Differential equations with a small parameter and the central limit theorem for functions defined on a finite Markov chain;Pinsky;Z. Wahrscheinlichkeitstheorie und Verw. Gebiete,1968