Morph question.
 

I have a quick question. I wanna start breeding leopardgecko but I am goin an extensive amount of research so I'll probly do it by next season. I don't wanna do it for profit. I just wanna experience the art of breeding all I would be happy with is to break even. Anyways I've also heard that there's some morph that cannot mix. Why is that? And is there any websites or books that I can check out to see what morph I can breed and cannot and why? Thank you!