“…A. Bakhtin (see [8]) and S. Czerwik (see [15] and [16]). In the last years a lot of fixed point results in the framework of b-metric spaces have been obtained (see, for example, [1], [7], [9], [11], [12], [17], [27], [28], [29], [31], [40], [41], [42], [44], [46], [47], [49], [50], [51], [55], [56] and [59]). …”