There're thousands of great books, but some of them had turned to be great coaches for me at some point. Maybe you find here the answers or inspiration you're looking for...
P. S. I don't have any financial interest in sharing my book-experience here. So feel free to take a look:)))
The Present Process
A good friend of mine recommended me this one, when my life looked way too complicated to me. So, I took the challenge (I didn't have much of inner peace to lose:))) and accomplished not only the theoretical part of it, but the whole Process (let's say, a Boot Camp Self-Development) as well. Several times. It was soooo challenging, but, as the author says, it's not about feeling yourself better, it's about better feeling yourself:) Result: more clearness in my feelings and behavioural patterns, as well as better connection with my real centre, real me.
Full Body Presence
Back into your body, back in here and now. Learn how to ground yourself, how to feel from deep inside what is actually going on in your system, who's "driving your bus". There're no difficult steps, nor rituals, nor meditating on the top of the holy mountain somewhere in Himalayas. Just read, listen, feel, explore and enjoy, whole day long, no matter what you do at this very moment.
The Yoga Mind
It was for me a great relief to find this book after I'd tried to find my way in the yoga philosophy, reading "The Yoga Sutras of Patanjali" (and fell every time asleep halfway my reading being confused by the complexity of this matter:)))
In this book, instead, you find all "need to know" about yoga philosophy and yoga background on a very easy and understandable way, so it can be the first step in your "yoga-philosophy- journey" (or maybe you find out it was just enough:)))
The Polyvagal Theory in Therapy: Engaging the Rhythm of Regulation
Knowing how our nervous system works is a key to understanding of our own behavioural reactions and reactions of others. It gives us the insights of how we can regulate and co-regulate so we don't blame ourselves for things we've done or haven't done (the main purpose of our nervous system is just to keep us safe, and it doesn't matter for our body at some point if we fight, flight or freeze), but see the patterns resultant of these biological reactions and get a possibility to break through them, creating more constructive ways of expressing ourselves. Thanks to the Polyvagal Theory we either learn what our triggers are and why the meditation and breathing techniques have such a great ability to calm us down and to bring clarity in our experience.