Ramana MaharshiRestraining the mind from going outside [through the senses], and fixing it always in its Source, Self, which is known as the Heart, so that the vain ‘I’-thought will not rise again, is the Atma-Vichara [Self-enquiry].

Ramana Maharshi

Māṇḍūkya Upaniṣad Reference Materials:

Video/Audio Lectures

Swami Tadatmananda
8 classes (~60 mins each)

Swami Paramarthananda
78 classes (~55 mins each) 1, 2, 3, 4, 5, 6

Swami Sarvapriyananda
4 classes (~60 mins each)

Swami Anubhavananda
6 classes (~75 mins each)

Mandukya Upanishad (Agama Prakarana)2 of 6 @ Bengaluru 2015 (English) 03683 NR YTC

Swami Sarvapriyananda
Who Am I? (~90 min talk) (Intro only. Must compliment with others below.)

Swami Sarvapriyananda at IITK - "Who Am I?" according to Mandukya Upanishad-Part 1

Swami Tattwamayananda
44 classes (~60 mins each)

Mandukya Upanishad Class 2

Swami Rama
8 classes (~75 mins each)

Mandukya Upanishad (2/8) Swami Rama

Swami Paramananda Bharti
~15 classes (~90 mins each)

001 Mandukya Upanishad