Mozart's Missa in C K. 317, erroneously dubbed the "Coronation Mass," is among the most popular and most often performed works in this genre. The autograph of the Mass was regarded as having been lost following the end of World War II, but was discovered at the end of the 1970s. It is now preserved among the musical treasures contained in the Biblioteka Jagiellonska in Kraków. Ulrich Leisinger, the editor, prepared the edition based upon what is, without a doubt, this only authentic source, although additionally in the Critical Report he has also consulted an early copy of the Mass (by Fügerl), since such later copies often help to clarify questions concerning historical performance practice.