Kundalini Tantra by Swami Satyananda Saraswati is an extensive introduction to both yoga and tantra. Kundalini yoga is a part of the tantric tradition. From the foreword:
“Even though you may have already been introduced to yoga, it is necessary to know something about tantra also. Since ancient times, the wise men have realized that mind can be expanded and that experiences do not necessarily depend on an object. This means that if somebody is playing music, I can hear it, and if somebody has painted a picture, I can see it, but I can also see if there is no picture, and I can hear if there is no music. This is also a quality of man’s personality which has been ignored in the last 150 to 200 years.”
Download Kundalini Tantra by Swami Satyananda Saraswati here (409 pages):
Sorry folks, I had to remove this book because of some possible copyright issues. I will look closer at the matter and let you know.