“…In recent years, this problem attracted the attention of many authors, putting an increased effort in the construction of new examples. As a result, we have now examples in the literature for all degrees 2 ≤ d ≤ 12 and d = 14, 16, 20, 24, 27, 32 and 36, see [11,13,14,[16][17][18][22][23][24][25] and [19].…”