There is a little book by Osho called Compassion, and I haven't read it but I am pretty sure The Art of Happiness by the Dalai Lama would go into it in some detail. My own personal favourite is a book called Cutting Through Spiritual Materialism by Chogyam Trungpa but its kind of weird and a bit obscure LOL. If you find those first two books that will definitely start you on your way!