Written by Israel Isserlin (1390 - 1460), Terumat HaDeshen is a work of responsa - letters written to a rabbi along with the subsequent response. Rabbi Isserlin was an influential rabbi in medieval Austria and Terumat HaDeshen serves as an important source of Ashkenazic practice. Rabbi Moses Isserles used Terumat HaDeshen as one of his sources for his work, HaMapah, which is a gloss to the Shulchan Arukh that discusses differences in Sephardic and Ashkenazic customs.