Shita Mekubetzet - Rabbi Bezalel Ashkenazi (6 vol.)

One of the basic texts for every Talmudic scholar. Written in the 1500's, this work is a compilation of the opinions of the Rishonim in their study of Talmud and is arranged according to the tractates in Shas. Rabbi Bezalel did not merely quote from the Rishonim; he also explained them thoroughly. He amended the texts where errors crept in.