Sleep/Parenting Book Recommendations

lisac1017

Please recommend any sleep or parenting book you have found invaluable.

Apparently, I was too wrapped up in my high-risk pregnancy and reading all about the potential complications of that to figure out how exactly we were going to parent this little guy once he arrived. 

I'm big on having a routine, but not necessarily a strict schedule - I value the ability to be flexible.  Curious to hear what worked for others...

Thanks!