Books on meditation?
You can try reading:


THE TRUE POWER OF KANNI MEDITATION －The Essential Guide to Anapanassati &amp; Vipassana
Anapanasati: Mindfulness with Breathing - Unveiling the Secrets of Life
Mindfulness of Breathing and Four Elements Meditation
Right Mindfulness: Memory &amp; Ardency on the Buddhist Path


Breath meditation is covered in Ānâpāna,sati Sutta which you can directly read.