Eyn geystlich Gesangk Buchleyn ("A spiritual song booklet"), was the first German hymnal harmonised for choir, published in Wittenberg in 1524 by Johann Walter who collaborated with Martin Luther. It contains 32 sacred songs, including 24 by Luther, in settings by Walter for three to five parts with the melody in the tenor. Luther wrote a preface for the part books. The collection has been called the root of all Protestant song music. Source: Wikipedia (en)