Before We Are Born by Moore & Persaud is good indeed but it gets very confusing in the later chapters (the first 4-6 chapters are really good though). I'd say if you have a lot of time on your hands, then it would be better to read this book as your main text and use Langman's as your reference. I read the first 5 chapters from Moore's and the rest from Langman's along with some material online (and a few of those sites have already been mentioned by OncoCap).