Some reference on quadratic rings or introductory algebraic number theory.

Question

I have found many posts on this matter. But none of them fulfills my purpose. So I am describing my situation briely. I have read ring theory from Dummit & Foote. I have been reading some field theory from the book Galois theory by Rotman. I am particularly interested in quadratic integer rings. I've also read some articles on this and started to read the number theory book by Ireland and Rosen. I really liked the subject. But while reading some things didn't come to naturally, like when they introduced universal side divisors and proved some integral domains are not euclidean domains and when they introduced Dedekind-Hasse norm and proved R is a PID iff R has a D-H norm. These were especially the parts I liked the most. But the applications of these were really hard (very manipulative). I would really like to read more about this area. Although I don't want to start algebraic number theory now. Any introductory or intermediate reference or some expostiory articles will be helpful.