The Ashkenazi authorities, as well as those in Italy, were great admirers of Mordechai, and assiduously studied the "Mordechai" and recognized its authority as a source of Halakha. Moses Isserles lectured on the "Mordechai" in his yeshivah, and many of his responsa are devoted to questions regarding difficult passages of the book. Its status was such, that the "Mordechai" is one of the sources of the "Shulchan Aruch" of Joseph Caro. In Italy and Poland, where the "Mordechai" was especially studied, a whole "Mordechai" literature came into existence.