al-Qawaa'id al-Mushtarakah bayna Usool al-Fiqh wa al-Qawaa'id al-Fiqhiyyah was orginally a Doctor Thesis written by ash-Shaykh Sulayman ar-Ruhaily (Haafidhullaah ta'alaa) which explains some of the Qawaa'id that are shared between both sciences (Usool al-Fiqh and Qawaa'id al-Fiqhiyyah). Printed by Dar al-Miraath an-Nabawee in two volumes on Yellow paper.