E.A. van Doorn, A.I. Zeifman and T.L. Panfilova,
Bounds and asymptotics for the rate of convergence of birth-death processes.
Teor. Veroyatnost. i Primenen. 54 (2009) 18-38 (in Russian).
[pdf file Memorandum 1882]
P. Coolen-Schrijner and E.A. van Doorn,
Orthogonal polynomials on R+ and birth-death processes with killing.
pp. 726-740 in: Difference Equations, Special Functions and Orthogonal Polynomials,
Proceedings of the International Conference (25-30 July 2005, Munich, Germany).
S. Elaydi, J. Cushing, R. Lasser, A. Ruffing, V. Papageorgiou and W. Van Assche,
eds, World Scientific Publishing, Singapore, 2007.