Ta'liq ala l-Qawa'id wa l-Usul al-Jami'a - al-Uthaymin

Explanation by Shaykh al-Uthaymeen, of the work of his Shaykh as-Sa'di in the rules of Usool al-Fiqh, which can be translated as The rules, the overall bases, the distinctions and the original and beneficial subdivisions.

Very nice Saudi official edition.