The 'Who Am I?' approach is the cornerstone of Advaita Vedanta which is explained nicely in these lectures:

1. Who Am I — Part I (97 mins, YouTube) and Who Am I — Part II (96 mins, YouTube) by Swami Sarvapriyananda (monk at Ramakrishna Order) at IIT Kanpur, 2014.

   Swami Sarvapriyananda has dozens of lectures online. Another lecture that I really liked is an exposition of Bhakti Marga (the Path of Devotion): The Way of Love (62 mins, 2017).

2. Sadhana (57 mins, YouTube) by Swami Advayananda (President, Chinmaya International Foundation), 2015.

   This lecture is helpful in understanding the connections between Advaita Vedanta (jnana marga) and mantra-based meditation (typically associated with bhakti marga).

1. Atma Shatkam by Adi Shankaracharya.
2. Ramana Maharshi (1879 - 1950), an Indian sage from Tamil Nadu, used to encourage practitioners to quieten their minds using whatever meditative practice they believed in, then notice the first thought that occurs and enquire 'To whom does this thought arise?' See Who Am I? by Ramana Maharshi. Basically, Ramana Maharshi's technique is a two-step process: first develop the ability to see mental phenomena like thoughts, then understand that 'I am the experiencer / witness' of mental phenomena like thoughts. This helps us understand that 'I am not the mind'.

   Ramana Maharshi advocated study of several ancient texts that are listed here. He translated a few himself. Some others were translated by his contemporaries / students and Ramana Maharshi approved of them. Two of these texts are Ashtavakra Gita and Tripura Rahasya (see below).

3. Ahtavakra Gita: Sri Ramakrishna and Ramana Maharshi are two Indian saints from recent years whose biographies and teachings are available in English. Both of them recommended Ashtavakra Gita to those who could grasp it. An English translation is found here. Swami Sarvapriyananda recommends translation by Thomas Byrom.
4. Tripura Rahasya is another book recommended by Ramana Maharshi. This translation was approved by Ramana Maharshi.

   'Tripura' means 'the three cities' which is a reference to the three states of our daily experience (waking state, dream state and deep sleep). 'Tripurari' is a combination of 'Tripura' (the three cities) and 'Ari' (enemy / destroyer). 'Tripurari' actually means 'one who destroys the illusion that the three cities are separate from us." In other words, 'Tripurari' refers to the one who teaches / understands 'non-duality' or 'Oneness'. The word 'Rahasya' simply means 'mystery'.

5. Panchadasi by Vidyaranya Swami is recommended by Swami Sarvapriyananda. Here is a copy at Amazon.

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