Takhreej al-Furu' 'ala al-Usool تخرج الفروع على الأصول by al-Imaam Abee al-Manaaqib Shihaab ad-Deen bin Mahmoud bin Ahmad az-Zanjaanee (Rahimahullaah). This is a fiqh book that is one of its kind. It was written at a time when blind following was prevalent and there were no Ulemaa' in Baghdad after the Death of al-Imaam at-Tabari that were returning to the Qur'an and Sunnah for guidance. az-Zanjaanee was a light in the darkness and a signpost in the path of knowledge. 

This book in unique as it begins with an Issue in Usool and connects with its its branches  in every principle. It also mentions fundamental proofs from two different points of view and connects its emerging branches back to its origin.  Printed on 409 pages of yellow paper.