This is an excellent introduction to Usool-ul-Fiqh by Imam as-Sa’di rahimahullaah, explained by Sh at-Ta’muri hafizahullaah (translated by Abu Talhah rahimahullaah).

Usool-ul-Fiqh is defined as:

Study materials:

Biography of Imaam as-Sa`di

Risaalah Lateefah

Translation

Explanation by Sh at-Ta`muri

Audios (in English):

usool-ul-fiqh 10-02-02

usool-ul-fiqh 10-02-09

usool-ul-fiqh 10-02-16

usool-ul-fiqh 10-02-23

usool-ul-fiqh 10-03-02

usool-ul-fiqh 10-03-09

usool-ul-fiqh 10-03-16

usool-ul-fiqh 10-03-23

usool-ul-fiqh 10-03-30

usool-ul-fiqh 10-04-13

usool-ul-fiqh 10-05-04

usool-ul-fiqh 10-05-11