1. Feller, W. The Birth and Death processes as diffusion processes. J. Math Pures Appl., 9: 301–345 (1959)
2. Gao, P. The birth and death processes with zero as their absorbing barrieer. Acta Math. Appl. Sinica., 2(4): 292–303 (1985)
3. Wang, Z.K. Classification of all birth and death processes. Science report of Universities. Phys.-Math. Science, 4: 19–25 1958 (in Russion)
4. Wang, Z.K., Yang, X.Q. The Birth and Death Process and Markov Chains, 2nd Ed. Science Press, Beijing, 2005
5. Wang, Z.K., Yang, X.Q. The Birth and Death processes and Markov chains. Springer-Verlag, Berlin, 1992