1. A direct proof of a fundamental theorem of renewal theory;Cox, D. R.;Skand. Aktuarietidskr.,1953
2. Discrete potential theory and boundaries;Doob, J. L.;J. Math. Mech.,1959
3. Application of boundary theory to sums of independent random variables.;Doob, J. L.,1960
4. Processus de Markoff en cascade;Hennequin, Paul-Louis;Ann. Inst. H. Poincar\'{e},1963