Cheng-Yuan Ku Din-Yuen Chan Lain-Chyr Hwang Optimal reservation policy for two queues in tandem. 27-30 2003 85 Inf. Process. Lett. 1 http://dx.doi.org/10.1016/S0020-0190(02)00334-4 db/journals/ipl/ipl85.html#KuCH03