“…Essential role in investigation of the queues operating in a RE was played by Neuts who investigated the M/M/1 type queue operating in a RE, see [12], and the M/SM/1 type queue, see [13], by means of the matrix analytic methods. As early works devoted to investigation of different queues operating in the RE papers [14][15][16][17][18][19][20][21][22] can be cited.…”