Finitely presented subgroups of systolic groups are systolic Gašper Zadnik (2014) Fundamenta Mathematicae We prove that every finitely presented subgroup of a systolic group is itself systolic.
From a 1-rotational RBIBD to a partitioned difference family. Buratti, Marco, Yan, Jie, Wang, Chengmin (2010) The Electronic Journal of Combinatorics [electronic only]