Dzogchen: Four introductory texts on Dzogchen

These books are meant as introductions to the Mahayana Buddhist system know as Dzogchen. There are indications that Dzogchen is a practice that is hundreds of years older than Buddhism itself, but it has been incorporated as advanced techniques into  the practices of Tibetan Buddhism. The four books are from the Berzin Archiches, you might want to check it out. Download the ebooks here:

The Major Facets of Dzogchen

Introduction to Dzogchen

Fundamentals of Dzogchen Meditation

Brief History of Dzogchen