E. ALTMAN, T. JIMÉNEZ, AND G.M. KOOLE, On the comparison of queueing systems with their fluid limits. Probability in the Engineering and Informational Sciences, 15:165-178, 2001.
 S. BHULAI AND G.M. KOOLE, A queueing model for call blending in call centers. In Proceedings of the 39th IEEE CDC, pages 1421-1426. IEEE Control Society, 2000.
 A.K. ERLANG, Solutions of some problems in the theory of probabilities of significance in automatic telephone exchanges. Electroteknikeren, 13:5-13, 1917. In Danish.
 N. GANS, G.M. KOOLE, AND A. MANDELBAUM., Operational models of telephone call centers: a tutorial and literature review. Manufacturing & Service Operations Management, 2002. To appear.
 L. GREEN AND P. KOLESAR, The pointwise stationary approximation for queues with nonstationary arrivals. Management Science, 37:84-97, 1991.
 G. JONGBLOED AND G.M. KOOLE, Managing uncertainty in call centers using Poisson mixtures. Applied Stochastic Models in Business and Industry, 17:307-318, 2001.
 G.M. KOOLE AND H.J. VAN DER SLUIS, Optimal shift scheduling with a global service level constraint. IIE Transactions, 2002. To appear.
 G.F. NEWELL, Applications of Queueing Theory. Chapman and Hall, 1971.