Advaita Vedanta

Shankaracharya's commentaries, along with his hymns and other writings, are now made available online in original (Sanskrit) by Shringeri math.

Upanishads

1) Shankaracharya (1957). Eight Upanisads Vol 1 (S. Gambhirananda, Trans.). Advaita Ashrama.
2) Shankaracharya (1957). Eight Upanisads Vol 2 (S. Gambhirananda, Trans.). Advaita Ashrama.

Accurate, concise english translations of Shankaracharya's commentaries on eight of the principal upanishads: Isa, Kena, Katha, Taittariya (vol. 1) and Aitareya, Mundaka, Mandukya (with Karika), Prasna (vol. 2).

1) Isshadi Nau Upnishad Shankar Bhashya Sahit
2) Chandogya Upanishad
3) Brihadaranyak Upanishad
Gita Press, Gorakhpur

Hindi translation of the commentaries of Shankaracharya of eleven principal upanishads. Excellent, nuanced translations.

Bramhasutra

Vishwarupananda, S. (1997). Vedanta Darshan (4 volumes, in Bengali). Udbodhan Karyalaya, Kolkata.

A complete, heavily annotated bengali translation of the Shankaracharya's commentary of the Bramha Sutra. The footnotes are often useful, particularly to clarify doubts regarding Mimansa and Nyaya.

Shankaracharya (1956). Bramhasutra Bhasya (Sw. Gambhirananda, Trans.). Advaita Ashrama.

Accurate english translation of Shankaracharya's commentary.

Gita

Swami, Gambhirananda (1984). Bhagavad Gita: With the commentary of Shankaracharya. Advaita Ashrama.

English translation

Shrimad Bhagwat Gita (ShankarBhashya Hindi Anuvad Sahit) (2022). Gita Press, Gorakhpur.

Hindi translation