I'm look at the special linear group and have a question: Is that $SL(2,3)$ have only $4$ normal subgroup? and how to prove the part "only"?
I can see that the two triviral subgroups, the centre and there is a 2-Sylow subgroup are all normal in $SL(2,3)$, but are there another normal?
Thank for anwser my question.