My favorite book for this age is Parenting with Purpose by Lynda Madison. It's out of print, but it's available cheap as a used book. I like it because it distinguishes between 1 year olds, 2 year olds, 3 year olds and 4 year olds. It does talk about using time outs and rewards for 4 year olds, which some people who do GD don't like. However, I think you can still get a lot of out of it, especially for the younger ages. A lot of discipline books seem to be written for the 3+ age group, and there aren't many that focus on discipline for such a young age.
I also like it because it talks about two important things: Figuring out what your parenting philosophy or purpose is, before you do any discipline. She makes the point that you can do all the techniques in the world (time out, rewards, making amends, etc), but if you don't know why you're doing these things and have a clear purpose, they won't be effective.
For example: Thinking about why I was doing time out helped me to get a grip on what I was doing, and apply it more effectively. What I discovered by doing this was that I wanted to use time-outs as a cooling off period. In reality though, I was sending our son to his room for pretty arbitrary things. So, by thinking about what I wanted, I was able to think before I sent him off to his room "do we need to cool off?", if so, we took a time out. Usually though, we didn't, or maybe mom did, and he didn't. So, then I'd take myself off for a timeout. This reduced the amount of times I was using it, and increased it's effectiveness. It wasn't time out as punishment anymore, it was "we need a break to regroup". Both my kids will now stomp off to their rooms when they're mad and need a break. I don't mind the stomping and the door slamming because despite those, they're demonstrating that they've learned to take a break when they need it.
The second important thing the author talks about is what's developmentally appropriate. She gently reminds us that 1 year olds aren't doing these things to be defiant, they're doing them because that's how they learn.
Both of these are good things to think about, even if you don't read this book.
another good book (that is in print) is: Becoming the Parent You Want to Be: A Sourcebook for the First Five Years. Again, I like it because it talks about toddlers as well as older kids.