poles and s-planes

[urosuros]

Hello good people of sdiy ,
there are several student questions I would like to ask :
What is s-plane position of poles and zeroes of  4pole moog and three pole
303 filters ?
I dont expect anyone to draw it and post it to list but can someone  please
tell me
where can I find it on net ? Also , root-locus diagrams ? On common sense
under normal conditions all poles should be imaginary , but what happens
with high resonance settings ? Selfoscilation ( instability ) should happen
when poles have just imaginary part in ideal conditions but in real cases
poles would enter ( more or less ) right half of s-plane , right ?
One of my professors told me that three pole transfer function is
inherently much , much more instable that two pole ?
Also he told me that instability could cause sqare wave oscilations not just
sine wave resonant oscilations . Has anyone experienced this in filters ?
And finaly are there any other three pole filters other than 303 ?
Was this discused earlyer ( I'm just two months on list ) ?
Thanks in advance
Uros