Chornomaz, B.O. 2017. Lower bound on the number of meet-irreducible elements in extremal lattices. Visnyk of V. N. Karazin Kharkiv National University. Ser. Mathematics, Applied Mathematics and Mechanics. 86, (Nov. 2017), 26-48. DOI:https://doi.org/10.26565/2221-5646-2017-86-04.