Is there any reference for collineation groups of finite projective planes?
By collineation of a projective plane $\pi=(P,L,i)$ I mean a bijective function $f:P\to P$ which preserves collinearity.
Are there theorems like "collineation groups of finite projective planes are solvable" or "have odd order" or something similar? I can't find anything online about this topic.
Also, if we consider maps $f:P\to P$ which only preserve incidence, what can we say?
Thanks!