Studying Owls

I have been preparing for owl season by listening to owls.  It's not easy.  Barred owls are easy.  Great horned owls are pretty easy.  But the other eight owls in Minnesota are confusing.  Great Gray?  I don't know what they sound like.  And I've gone looking for them too.  I did see a northern hawk owl once and saw it's angry face looking back at me but I never heard it ululululul or kip kip kip.  Long eared owls say who who who 2 to 4 seconds apart.  Short eared owls give asthmatic barks.  Barn owls screech and screech owls whinny like a horse. Or a ghost.  Or a ghost horse.  Or a bouncing ball. Man, I got more studying to do if I'm going to pass that owl quiz.