I. The single server queue GI/G/1 -- 1.1 Definitions -- 1.2 Regenerative processes -- 1.3 The sequence wn, n = 1,2,… -- 1.4 The process {v, t ?[0, ?)} -- 1.5 The process {?t, t ?[0, ?)} -- 1.6 Applications to the GI/G/1 queue -- 1.7 Some notes on chapter I -- II. The M/G/K system -- 2.1 On the stationary distribution of the actual and virtual waiting time for the M/G/K queueing system -- 2.2 The M/G/K loss system -- 2.3 Proof of Erlang’s formula for the M/G/K loss system -- III. The M/G/1 system -- 3.1 Introduction -- 3.2 Downcrossings of the vt(K) -process -- 3.3 The distribution of the supremum of the virtual waiting time vt(?) during a busy cycle -- 3.4 The distribution of the downcrossings 8l -- 3.5 Derivation of the stationary distribution of the vt(K) - process, I -- 3.6 Derivation of the stationary distribution of the vt(K) - process, II -- 3.7 Some remarks on the actual and virtual waiting time processes -- References.