Beltrán, A.; Felipe Román, María Josefa; Melchor, C.(Springer-Verlag, 2018)
[EN] We prove that if a finite group G contains a conjugacy class K whose square is of the form 1¿D, where D is a conjugacy class of G, then ¿K¿ is a solvable proper normal subgroup of G and we completely determine its ...