Parents! What book(s) would you recommend on discipline?

I have twin one year old boys, and I'm interesting in reading a book about introducing discipline, also how to discipline in a healthy, effective manner. There are so many books to choose from! What book(s) would you recommend - or NOT recommend reading and why? Thank you!
Update: My husband and I are seeking books on discipline because neither of us had a lot of exposure to children before our own and we want some credible, general guidelines on how to best deal with this subject.
Update 2: :) Thanks again!
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