“…The exact values for the crossing numbers of G + D n for all graphs G of order at most four are given by Klešč and Schr ötter [21]. Also, the crossing numbers of the graphs G + D n are known for a lot of graphs G of order five and six [1,5,7,10,11,12,13,15,17,18,19,20,22,23,26,27,29,30,33,34,35,36]. In all these cases, the graph G is connected and contains usually at least one cycle.…”