“…This result was soon followed by many related ones, due to Barát, Foldes, E. K. Horváth, G. Horváth, Lengvárszky, Németh, Pach, Pluhár, Pongrácz, Šešelja, Szabó, and Tepavčević. The results of these authors, written alone or in various groups, range from triangular boards to the continuous case and from lattice theory to combinatorics, see [6], [21], [24], [25], [26], [28], [29], [30], [32], [33], and some further papers not referenced here. Since [21] and [24] give good overviews on islands, we do not go into further historical details.…”