De Mari F.
Ukr. Mat. Zh. - 2004. - 56, № 10. - pp. 1419-1423
Let G be a Tarski-free group such that the join of all nonmodular subgroups of G is a proper subgroup in G. It is proved that G contains a finite normal subgroup N such that the quotient group G/N has a modular subgroup lattice.