Secret Doctrine  

https://universaltheosophy.com/hpb/secretdoctrine.html

Proem to the Secret Doctrine 

https://www.phx-ult-lodge.org/Aproem.htm

Isis Unveiled

Vol I   https://www.phx-ult-lodge.org/isis_unveiled1.htm

Vol II  https://www.phx-ult-lodge.org/Isis_Unveiled.htm

Theosophical Glossary   

https://www.phx-ult-lodge.org/Thegloss.htm

Voice of the Silence 

https://www.phx-ult-lodge.org/asound.htm

Key To Theosophy

 https://www.phx-ult-lodge.org/Aproem.htm

HPB Articles Vol. I, II, and III 

https://www.theosophy-ult.org.uk/wp-content/uploads/2018/10/HPB-Theosophical-Articles-Vols-1-2-3.pdf

Transactions of a Blavatsky Lodge

https://www.phx-ult-lodge.org/Transactions.htm

Five Messages 

https://www.phx-ult-lodge.org/five_messages.htm

Five Years of Theosophy

https://www.phx-ult-lodge.org/five-years.htm

Raja Yoga and Occultism

https://www.theosophy-ult.org.uk/wp-content/uploads/2019/08/Raja-Yoga-or-Occultism-H-P-Blavatsky.pdf

Dialogues on the Secret Doctrine 

https://www.theosophy-ult.org.uk/wp-content/uploads/2014/06/secret-doctrine-dialogues.pdf