Source: /cirosantilli/chevalley-groups-a-n-q

= Chevalley groups $A_n(q)$
{c}

They are the <finite projective special linear groups>.

This was the first infinite family of <simple groups> discovered after the simple <cyclic groups> and <alternating groups>. The first case discovered was <PSL(2, p)> by <Galois>. You should understand that one first.