My fave, (if you're aiming away from traditional discipline based on fear, rewards/punishment etc) is Alfie Kohn "Unconditional Parenting". It's pretty controversial compared to mainstream general parenting practices and you may not take all of it on board but I found it to be the most useful book I've ever read in getting me to question my own parenting style, the style I was raised with (which was hugely conditional) and the style I want to work towards. We don't take this approach every single minute but I strive to be unconditional and I have found it to really sit well with my approach to life and my other training and employment background.

The other one I read when DS was about a year old was Pinky McKay's Toddler Tactics - it has a huge number of practical strategies and down to earth discussion of typical toddler behaviours.