links for pdf of books
1) Muntaqa al-Akhbār by Majd ad-Deen ibn Taymiyyah
(A book on the hadith connected to Fiqh rulings)
2) Ighafah al-Lahfan by ibn al-Qayyim
(A book of the trap and tricks of Shaytan and how to avoid them)
3) Kitab Al Kabā'ir by Muhammad bin Abdul Wahhab
4) Sharh Aqīdah at-Tahawiyyah by ibn Abil Izz
6) Fathul Majeed Sharh Kitab at-Tawheed by Abdur Rahman bin Hasan bin Muhammad bin Abdul Wahhab