Introduction to Upnishads : Mandukya Upanishad - True Self (Atman) and Omkara
(Reklamlänk)
Mandukya Upanishad is attached to the Atharvaveda, and it is the smallest of the 10 major Upanishads. However it deals with very significant concepts such as 4 quarters of Atman (self), the true nature of Atman and the role of Omkara in achieving it.