Atereth Tzvi - Nachalath Tzvi [commentary to Shulchan Aruch - Orach Chaim].

R. Tzvi Katz lived in Poland during the first half of the 17th century. He studied in Cracow under R. Yoel Sirkes (the Ba”Ch) and was a colleague of the Tosfoth Yom-Tov. The work here is divided into two: Atereth Tzvi explains the words of the Shulchan Aruch while Nachalath Tzvi delves into solving difficulties in the words of the Geonim and Rishonim. The work swiftly gained popularity and is often cited by authorities such as the Chida and the Pri Megadim.