Tanqih al-Fusul fi 'Ilm al-Usul - Al-Qarafi (Harakat)

This book is very important in the science of Usool, indeed this book is the basis of many books that were written after it. It is a summary based on 4 main sources: Al-Umdah by Qadhi Abdeljabbar, Al-Mu'tamad by Abi Husayn al-Basri, Al-Burhan by Imam al-Haramayn al-Jouwayni and Al-Mustasfa by Al-Ghazali.