Koichi Nakade Masamitsu Ohnishi Toshihide Ibaraki Katsuhisa Ohno On the average optimality of circular assignment policy. 241-254 1992 11 Queueing Syst. 3 http://dx.doi.org/10.1007/BF01164004 db/journals/questa/questa11.html#NakadeOIO92