“…Beineke and Ringeisen in [4], Jendrol' andŠčerbová in [9] determined the crossing numbers of the Cartesian products of all graphs on four vertices with cycles. Klešč in [10], [12], [13], [14], Klešč, Richter and Stobert in [15], and Klešč and Kocúrová in [16] gave the crossing numbers of G C n for several graphs of order five. Harary et al [8] conjectured that the crossing number of C m C n is (m − 2)n, for all m, n satisfying 3 ≤ m ≤ n. This has been proved only for m, n satisfying n ≥ m, m ≤ 7 ( [1], [2], [3], [4], [5], [15], [17], [18]).…”