Om Yoga Its Theory and Practice by Swami Nirmalananda Giri

Om Yoga Its Theory and Practice by Swami Nirmalananda Giri published in 2006 by Atma Jyoti Press is an introduction to classic yoga as thought in the Bhagavad Gita.  It goes into details on breath and sound in both yoga and meditation. The book also has an extensive glossary. Download it here (113 pages):

Om Yoga Its Theory and Practice by Swami Nirmalananda Giri