Regarding Authenticity

More than three hundred works — commentaries, expositions, and poetry — are attributed to him.
Most of these are not accepted as authentic. His masterpiece is the Brahmasutrabhasya, the commentary on the Brahmasutra.
Sankara wrote commentaries on the Brihadaranyaka, Chandogya, Aitareya, Taittiriya, Kena, Isa, Katha, Mundaka, Prasna, and Mandukya Upanishads. The Upadesasahasri is the only non-commentarial work whose authenticity has been conclusively demonstrated.
S. Mayeda. A Thousand Teachings the Upadesasahasri of Sankara

This work assigned to Samkara is a commentary on the most well known Smriti text of Bhagavad Gita
Payyappilly. P. Joseph. The Concept of Man in the Advaita Vedanta of Sankara: An Inquiry into Theological Perspectives

Info: Most files are hosted externally. Their permanent availability is not guaranteed!

UPDATES:

- FEB 2021: Some revisions (Hishi)

CATEGORIES (currently ~ 200 references) Update: February 2021

1. Paramaguru Sri Gaudapadacarya (& Mandukya Karika)
2. Brahma Sutra (Nyaya prasthāna)
3. Bhagavad Gita (Smṛti prasthāna)
4. Principal Upanishads (Śruti prasthāna)
5. Upadeśasāhasri
6. References & Encyclopedias
7. About Adi Shankaracharya
8. Sri Sureshwaracharya
9. Sri Totakacharya
10. Sri Padmapadacharya
11. Sri Hastamalakacarya
12. The classic debate between Mandana Misra and Adi Shankara
13. Works attributed to Adi Shankaracharya (A Selection)
14. Other Advaita Vedanta Topics (Avidya & Maya, Advaita & Buddhism, etc.)
15. Post Shankara Periods (Vivaraṇa & Bhāmatī Schools)
16. Scriptures by later Advaitins (Post-Sankara Advaita, Selections) - ENGLISH
17. Additional References
18. Helpful Articles
19. Related to Sanskrit

1. Paramaguru Sri Gaudapadacarya (& Mandukya Karika)

1. Early Advaita Vedanta And Buddhism, Richard King
   

2. From Early Vedanta To Kashmir Shaivism Gaudapada Bhartrahari And Abhinavagupta, Natalia Isayeva

3. Gaudapada A Study In Early Advaita, Mahadevan T. M. P.

4. Gaudapada's Argument for Irrationality of Realistic Pluralism, Domenic Marbaniang

5. Mandukya Karika, Swami Gambhirananda

6. Method Of Early Advaita Vedanta A Study Of Gaudapada, Sankara, Suresvara And Padmapada, Michael Coman

7. Samsayaghni: Book Which Explains the Difficult Portions of the Mandukya Upanishad, Swami Paramanand Bharati

8. The essential Gaudapada, Gangolly, D. B. (Highly recommended)

9. The Agamasastra Of Gaudapada, Vidhushekhara Bhattacharya

10. The Mandukyopanishad With Gaudapadas Karikas And The Bhashya Of Sankara, Manilal N. Dvivedi

    
    

2. Brahma Sutra (Nyaya prasthāna)

Brahma Sutra Shankara Bhashya (Sanskrit only!)

https://advaitasharada.sringeri.net/display/bhashya/BS#BS_C01_S01

Brahma Sutra Shankara Bhashya, V.M. Apte
https://archive.org/details/BrahmaSutraSankaraBhashyaEngVMApte1960/page/n197/mode/2up

Brahma Sutra Bhasya, Swami Gambhirananda

https://archive.org/details/brahma-sutra-swami-gambhirananda/page/462/mode/2up

https://estudantedavedanta.net/Brahma_Sutra_Swami_Gambhirananda.pdf

Brahma Sutra Bhashyam George Thibaut, Part 1

https://archive.org/details/SutraBhashyamThibaut

Brahma Sutra Bhashyam George Thibaut, Part 2

https://archive.org/details/in.ernet.dli.2015.22559

 2.1 Brahmasutra & Brahmasutra Catussutri (Supplementary)

1. Brahmasutra Catussutri, Swami Paramananda Bharati
2. The Brahma-sutras Of Badarayana Chapter II.1 & II.2 Belvalkar, S. K.

3. Brahma Sutras According To Sri Sankara (abridged) by Swami Vireswarananda

4. Vedānta Explained: Śaṅkara's Commentary On the Brahma-sūtras, Vol. 1

5. Vedānta Explained: Śaṅkara's Commentary On the Brahma-sūtras, Vol. 2

6. Brahmasutra Catussutri As Taught By Swami Dayananda

7. Sankara's Sutra-Bhashya (Self-Explained) (Highly recommended)

3. Bhagavad Gita (Smṛti prasthāna)

Bhagavad Gita Bhashya (Sanskrit only)

https://advaitasharada.sringeri.net/display/bhashya/Gita

Bhagavad Gita with the Commentary of Sri Shankaracharya, Alladi Mahadeva Sastri
https://archive.org/details/Bhagavad-Gita.with.the.Commentary.of.Sri.Shankaracharya/page/n349/mode/2up

https://archive.org/details/BhagavadGita.with.the.Commentary.of.Sri.Shankaracharya_201708/page/n409/mode/2up | Alternative

Bhagavad Gita with English Translation of Sri Sankaracharya's Sanskrit Commentary, Swami Gambhirananda (without Intro)

http://michaelsudduth.com/wp-content/uploads/2013/01/Srimad-Bhagavad-Gita-Shankara-Bhashya-English.pdf

Srimad Bhagavad Gita Bhasya of Sri Sankaracarya

https://estudantedavedanta.net/Bhagavad-Gita-Bhashya-of-Sankaracharya-Krishna-Warrier.pdf

Bhagavad Gita Dictionary

https://archive.org/details/GitaDictionary/page/n113/mode/2up

4. Principal Upanishads (Śruti prasthāna)

Eight Upanishads Vol. 1 (Isa, Kena, Katha, and Taittirīya Upanishad), Swami Gambhirananda

https://archive.org/details/EightUpanishadsVol.1BySwamiGambhirananda/page/n199/mode/2up

Eight Upanishads Vol. 2 (Aitareya, Mundaka, Mandukya Karika and Prasna Upanishad), Swami Gambhirananda

https://archive.org/details/EightUpanishadsVol.2BySwamiGambhirananda/page/n527/mode/2up

Mandukya Upanishad & Karika with Shankara Bhashya, Swami Nikhilananda
https://archive.org/details/MandukyaUpanishadKarikaWithShankaraBhashya-SwamiNikhilananda/mode/2up

Brihadaranyaka Upanishad with Shankara Bhashya, Swami Madhavananda
https://archive.org/details/in.ernet.dli.2015.20823/page/n751/mode/2up

Brihadaranyaka Upanishad Overview T.N.Sethumadhavan

Chandogya Upanishad with Shankara Bhashya, Ganganath Jha
https://archive.org/details/Shankara.Bhashya-Chandogya.Upanishad-Ganganath.Jha.1942.English/mode/2up

Aitareya &Taittiriya Upanishads with Shankara Bhashya

https://archive.org/details/AitareyataittiriyaUpanishadsWithShankaraBhashya-English/page/n1/mode/2up

Kenopanishad_Vakhya_Bhashya

Kenopanishad_Vakhya_Bhashya, Swami Bodhatmananda

5. Upadeśasāhasri

Upadesasahasri, Swami Jagadananda

https://archive.org/details/in.ernet.dli.2015.310989

Upadesa Sahasri Of Sanakaracharya A Thousand Teachings, Mayeda

6. References & Encyclopedias

1. A Dictionary of Advaita Vedanta Swami Harshananda

2. Encyclopedia Of Indian Philosophy Volume 3 Advaita Vedanta Up To Samkara And His Pupils, Karl H. Potter

3. Encyclopedia Of Indian Philosophy Volume 11 Advaita Vedanta from 800 to 1200, Karl H. Potter
   

4. Essential Vedanta A New Source Book Of Advaita Vedanta, Eliot Deutsch

5. Sankara Source Book Volume 1 - Sankara On the Absolute, AJ Alston
   

6. Sankara Source Book Volume 2 - Sankara On the Creation, AJ Alston
   

7. Sankara Source Book Volume 3 - Sankara On the Soul,  AJ Alston
   

8. Sankara Source Book Volume 4 - Sankara On Rival Views, AJ Alston
   

9. Sankara Source Book Volume 5 - Sankara On Disciple, AJ Alston
   

10. Sankara Source Book Volume 6 - Sankara On Enlightenment, AJ Alston

11. The essential Adi Shankara, Gangolly, D. B.

12. The Heart of Sri Samkara, Sri Sri Satchidānandendra Saraswati

13. The Method of the Vedanta by Sri Sri Satchidānandendra Saraswati, transl. AJ Alston
    

14. Elucidation of terms and concepts in Vedanta, S.N.Sastri

7. About Adi Shankaracharya

1. Acharya Sankara Of Kaladi A Story,  Madugula I. S

2. Life And Thought Of Sankaracharya, Govind Chandra Pande

3. Sankara Vijayas A Comparative & Critical Study, Dr. Antarkar W. R.

4. Sankaracharya & His Connection With Kanchipuram, Kuppuswami A.

5. Sankaras Date, R.M. Umesh

6. Sri Sankaracharaya His Life And Times Vol I, Aiyar, Krishnaswamy C. N

7. Three Great Acharyas Sankara Ramanuja And Madhwa, G. A. Natesan

8. Traditional Age Of Sri Sankaracharya, Nataraja Aiyer A., Lakshmi Narasmha Shastri

9. Śri Śaṅkara Bhagavatpāda Vṛttānta Sāra Sarvasva, Sri Sri Satchidānandendra Saraswati (Highly recommended)

10. Adi Sankara His Life & Times Discourses Of Chandrashekhara Saraswati, Mahadevan T. M. P.

11. Conquest of the Four Quarters: Traditional Accounts of the Life of Sankara, Bader

12. The Age of Sankara, by T. S. Narayana Sastry

8. Sri Sureshwaracharya

1. Sureshvaracharya's Brihadaranyaka Upanishad Bhashya Vartika (English, Complete)

2. The Realization of the Absolute - The "Naiskarmya Siddhi" of Sri Suresvara, A.J Alston
   

3. The Sambandha Vartika Suresvaracarya, T.M.P. Mahadevan

4. Taittiriya Upanisad Bhashya Vartika Of Suresvara, Balasubramanian R

9. Sri Totakacharya

1. Toṭakāṣṭakam

10. Sri Padmapadacharya

The Pancapadika of Padmapada (Translated into English), Rajasevasakta D. Venkataramiah

11. Sri Hastamalakacarya

1. Hastamalakiya Bhashya (Sanskrit only!)
   
2. Hastamalakiyam, Commentary in English on Hastamalakiyam, S.N. Sastri

12. The classic debate between Mandana Misra and Adi Shankara

Sankara Digvijaya Chapter 8 (Debate between Mandana Misra and Adi Shankara)

13. Works attributed to Adi Shankaracharya (A Selection)

1. Aparoksha Anubhuti By Sri Shankaracharya, Swami Vimuktananda

2. Atma Bodha of Sankaracharya, Menon P.N

3. Bhaja Govindam, Swami Nikhilananda

4. Drg Drsya Viveka, Swami Nikhilananda

5. Sankara On The Yoga Sutras, Trevor Leggett

6. Saundarya Lahari Of Sankaracarya, Subramanian V. K.

7. Select Works Of Sankara, S. Venkataramanan

8. Self-Knowledge (Atma Bodha) And Other Stotras, Swami Nikhilananda

9. Talks On Vivekachudamani, Swami Dayananda

10. Tattva Bodha of Sankaracharya, Svarupa Chaitanya

11. The Vedanta Doctrine Of Sri Sankaracharya, Alladi Mahadeva Sastri
    

12. The Imitation Of Sankara, Manilal N. Dvivedi
    

13. Vakyavritti and Atmajnanaopadeshavidhi of Sri Sankaracharya, Swami Jagadananda
    

14. Vedanta Through Shankars Prakarans, Swami Mahesananda Giri

15. Vedantic Ways To Samadhi (Drg Drsya Viveka), Swami Suddhabodhananda Sarasvati

16. Vishnu Sahasranama with the Bhasya of Sankaracharya, R. Ananthakrishna Sastry

17. Vivekachudamani, Swami Madhavananda

    
    

14. Other Advaita Vedanta Topics

 14.1 Advaita Vedanta & Buddhism

1. Advaita And Other Systems, Dr. P. K. Sundaram

2. Dialectic in Buddhism and Vedanta, Chandradhar Sharma

3. The Problem Of Two Truths In Buddhism And Vedanta, Sprung Mervyn

4. Vedantic & Buddhist Concept Of Reality As Interpreted By Sankara & Nagarjuna, Rama Chandra Jha

 14.2 Avidya & Maya

1. Ajnana, Malkani, G.R.

2. Avidya A Problem Of Truth And Reality, Solomon E. A.

3. Concept Of Maya, Devanandan P. D

4. Concept Of Maya By Ruth Reyna

5. Maya A Conceptual History, Dr. Arpita Mitra
   

6. Maya Divine And Human, Teun Goudriaan

7. Maya In Radhakrishnan's Thought Six Meanings Other Than Illusion, Donald Braue

8. Teaching Of Brahman Through TheAttributions Of Avidya And Maya, Sri Devarao Kulkarni

9. The doctrine of Māyā in the philosophy of the Vendānta, Shastri, Prabhu Dutt

 14.3 Different Topics (uncategorized)

1. A Few Thoughts On The Science Of The Self Or Atma Vidya, G. Ramachandra Aiyar

2. A History Of Early Vedanta Philosophy Vol. 1, Hajime Nakumara
   

3. A History of Early Vedanta Philosophy Vol. 2, Hajime Nakumara
   

4. A Realistic Interpretation Of Sankara Vedanta, Kokileswar Sastri

5. A Constructive Survey of Upanishadic Philosophy, R.D.Ranade

6. Accomplishing The Accomplished - The Vedas As A Source Of Valid Knowledge In Sankara, Anantanand Rambachan

7. Advaita A Critical Investigation, Srinivasa Rao

8. Advaitāmoda A Study Of Advaita And Visita Advaita, Michael Comans

9. Advaita and Visistadvaita A Study Of Vedanta Desika, Srinivasa Chari S. M.

10. Advaita Faith And Practice, Gundappa D. V

11. Advaita Vedanta An Introduction, Arvind Sharma

12. An Advaita Vedanta Perspective On Language, John Grimes

13. Advaita Vedanta Problems And Perspectives, Ramakrishna Rao

14. Advaita Vedanta, Venkatarama Iyer M. K.

15. Advaita Vedanta, R. Balasubramanian

16. An Introduction To Advaita Philosophy, Kokileswar Sastri

17. Aspects Of Advaita Advaita And Modern Thought, Ramaswami Sastri K. S

18. Bhakti In Advaita Vedanta Translation & Study Of Madhusudana Sarasvati's Bhaktirasayana, Lance Edward Nelson
    

19. Concept Of Self Luminosity In Advaita Vedanta, Dr. Girdhari Lal Chaturvedi

20. Consciousness In Advaita, Ramachandra Rao S. K.

21. Consciousness In Advaita Vedanta, William M. Indich

22. The Disinterested Witness - A Fragment Of Advaita Vedanta & Phenomenology, Bina Gupta

23. The Experimental Dimension Of Advaita Vedanta, Arvind Sharma

24. The Fundamentals Of Logic, Mahadevan T. M. P.

25. God In Advaita, Krishna Warrier A. G.

26. Hermeneutics Holography And Indian Idealism, Stephen Kaplan

27. Immediate Knowledge And Happiness, John Levy

28. The Purpose and Method of the Brahmavidya Ashrama, C. Jinarajadasa

29. The Jungian Myth And Advaita Vedanta, Carol Whitfield

30. Knowing Beyond Knowledge Epistemologies Of Religious Experience In Classical and Modern Advaita, Thomas Forsthoefel

31. Lights on Advaita: Selected Teachings of V. Subrahmanya Iyer

32. Limits Of Scripture, Anantanand Rambachan

33. The Making Of The Vedanta, Mainkar T. G.

34. Metaphysics Of Advaita Vedanta, Malkani G. R.

35. Mimamsa And Vedanta Interaction And Continuity, Johannes Bronkhorst

36. Outline of the Vedanta system of philosophy according to Shankara, Paul Deussen

37. Perceiving In Advaita Vedanta Epistemological Analysis & Interpretations, Bina Gupta

38. Philosophical Essays, Surendranath Dasgupta

39. Philosophy Of The Self, Ghanshamdas Rattanmal Malkani

40. The philosophy of Shankara, Maganlal A. Buch

41. Preceptors Of Advaita, Mahadevan T. M. P.

42. Relationalism: A Theory of Being, Joseph Kaipayil

43. Revelation and reason in Advaita Vedanta, K. Satchidananda. Murty

44. Sabda Pramana Word & Knowledge, Purusottama Bilimoria

45. Sea Shell As Silver A Metaphorical Excursion In To Advaita Vedanta, Arvind Sharma

46. The Self And Its States, Andrew O Fort
    

47. The Self As The Seer And The Seen A Phenomenological And Hermeneutic Study, Balasubramanian R.

48. Sense Perception In Science and Shastra, Sringeri

49. Sleep As A State Of Consciousness In Advaita Vedanta, Arvind Sharma

50. Studies In Vedanta, Kirtikar Rao Bahadur Vasudeva J.

51. The Advaita Tradition In Indian Philosophy, Chandradhar Sharma

52. The Concept Of Mukti In Advaita Vedanta, A.G.Krishna Warrier

53. The Existence Of God

54. The Fundamentals Of Vedanta Philosophy, Swami Pratyagatmananda

55. The Philosophy Of Advaita, T M P Mahadevan

56. The Quest After Perfection, M. Hiriyanna

57. The Schools Of Vedanta, P.Nagaraja Rao

58. The Self in Advaita, S. Y. Krishnaswamy

59. Tradition Of Advaita Essays In Honour Of Kalyanasundara Sastri, Balasubramanian R.

60. Tradition And Reflection Explorations In Indian Thought, Wilhelm Halbfass

61. Vedanta Sara Sangraha (Quintessence of Vedanta) Sri Anantendra Yati, T.M.P. Mahadevan

62. Vedantic Epistemology, Malkani G. R.

63. Vedic Concept Of Atman, Ramanathan A. S.

64. The World As Image, Arvind Sharma

65. Yoga, Enlightenment And Perfection Swami Vidyatirtha Sringeri

15. Post Shankara Periods (Vivaraṇa & Bhāmatī Schools)

A Critique on the Vivarana School, Bratindra Kumar Sengupta

https://archive.org/details/A.Critique.on.the.Vivarana.School

Bhamati And Vivaraṇa Schools Of Advaita Vedanta, P.S. Roodurmun

https://archive.org/details/bhamatiandvivaranaschoolsofadvaitavedantapulasthsoobahroodurmummlbdms_988_O

Misconceptions About Śaṅkara, Sri Sri Satchidanandendra Saraswati (Highly recommended)
http://adhyatmaprakasha.org/Volumes/PDF/english/007/index.pdf

Studies in Post-Samkara Dialectics, Ashutosh Bhattacharyya Shastri

https://archive.org/details/in.gov.ignca.7277

16. Scriptures by later Advaitins (Post-Sankara Advaita, Selections) - ENGLISH

Mandana Mishra (possibly Sureśvara):

The Advaita Vedanta of Brahmasiddhi. Allen W. Thrasher

Vācaspati Miśra:

1. The Bhamati Catussutri (on Śankara's Brahmasūtrabhāsya)

2. Vacaspati Misra On Advaita Vedanta. Dr. Hasurkar

3. Contribution Of Vacaspati Misra To Indian Philosophy
   

Prakasatman (Vivarana):

Prakasatman's Pancapadika-Vivarana

Sarvajnatman:

1. Pancaprakriya of Sarvajnatman

2. Samksepasariraka of Sarvajnatman

Śrīharṣa:

Khaṇḍanakhaṇḍakhādya

Sri Vidyāraṇya & Bharati Tirtha:

1. Pañcadaśī

2. Jivanmukti Viveka

3. Sarva-Darsana-Samgraha by Madhavacharya (Vidyaranya Swami). E.B.Cowell

4. Vivarana Prameya Sangrah (English)
   

Śaṃkarānanda:

1. The Philosophy of Sage Yajnavalkya: a free rendering of the Yajnavalkya-Kanda by Swami Brahmananda
   

2. Kausitaki Brahmanopanishad with Dipika, edited with translation by E. B. Cowell

Sadananda Yogendra Saraswati:

1. Vedāntasāra

2. A manual of Hindu pantheism, The Vedantasara. Transl. Jabob

Nṛsiṃhāśrama:

Bheda-Dhikkāra

Madhusūdana Sarasvatī:

1. Advaita-Siddhi (English)

2. Advaita-Siddhi (Sanskrit)

3. Siddhanta-Bindu

4. Vedantakalpalatika

Dharmarāja Adhvarindra:

1. Vedānta-Paribhāsā. Transl. Swami Madhavananda (English)
2. Vedānta-Paribhāsā (Sanskrit)

Appayya Dīkṣita:

1. Siddhanta Lesa Sangraha (English)
2. Siddhanta Lesa Sangraha (Sanskrit)

Sadasiva Brahmendra:

Advaita-rasa-Mañjari

Sri Chandrasekhara Bharati:

Sri Chandrasekhara Bharati Biography

Sri Satchidanandendra Saraswati Swamiji:

A lot of excellent works! http://adhyatmaprakasha.org/php/english_books.php

17. Additional References

Adhyatmaprakasha Karyalaya (Highly recommended)
http://adhyatmaprakasha.org

Madhaviya Shankara Digvijayam
https://www.sringeri.net/history/sri-adi-shankaracharya/biography/abridged-madhaviya-shankara-digvijayam

Prasthanatraya Forum & Bhashya
http://shankarabhashya.com

18. Helpful Articles

https://advaita-vedanta.org/articles/index.html

19. Related to Sanskrit

https://advaitasharada.sringeri.net/%E0%A4%97%E0%A5%8D%E0%A4%B0%E0%A4%A8%E0%A5%8D%E0%A4%A5%E0%A4%BE%E0%A4%83/ (Highly recommended)

https://sanskritdocuments.org/sanskrit/shankaracharya
https://www.gitasupersite.iitk.ac.in (Great)

https://sanskritdocuments.org (Great)

http://www.sanskritweb.net/sansdocs

http://www.sanskritebooks.org

http://gretil.sub.uni-goettingen.de/gretil.html (Great)

19.1 Sanskrit Dictionaries & Tools

http://www.andhrabharati.com/dictionary/sanskrit/

http://spokensanskrit.org

Cologne Digital Sanskrit Dictionaries
https://www.sanskrit-lexicon.uni-koeln.de

List of Sanskrit-English Dictionaries (MW, Apte, McDonell, etc.)
https://sanskritlibrary.org/cologne.html

Online Sanskrit Tools - TDIL-DC
http://tdil-dc.in/index.php?option=com_vertical&parentid=84&lang=en

Sanskrit Computational Tools
http://sanskrit.uohyd.ac.in/scl/