Chornomaz, B. O. “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, Vol. 86, Nov. 2017, pp. 26-48, doi:10.26565/2221-5646-2017-86-04.