This Book is Concerning the Jurisprudence (Fiqh) of Imam of the Sunna, Ahmad ibn Hanbal ash-Shaibani (may Allah be well pleased with him) by Shaikh al-Islam Imam al-Muwaffaq ibn Qudama (A.H. 541-620) was one of the luminaries of his day and age.
Hanbali Principles of Testing Hadith (Usul al-Hanabila Li Naqdil Hadith) is a concise but detailed text that covers most, if not all, issues related to the topic.