Finite groups of even orders all of whose fourth maximal subgroups are weakly $$s_{2}$$ s 2 -permutable

Acta Mathematica Hungarica - Let p be a prime number. A positive integer m is said to be a $$p'$$ -number provided $$p\nmid m$$ . Let G be a finite group, and let H be a subgroup of G. We say...