Watch these series of lectures of Swami Rama about Vedanta…
Online courses with Swami Jnaneshvara on this subject:
Om Mantra, the Heart of Traditional Yoga
Jnana Yoga, the Yoga of Contemplation
Yoga Nidra: Conscious Deep Sleep of the Ancient Sages
The Blended Path of Yoga, Vedanta, and Tantra
ARTICLES:
Contemplation: Sravana – Manana – Nididhyasana
Mandukya Upanishad: 12 verses on AUM Mantra
Gaudapada’s Karika with Mandukya Upanishad