Anastasius Bibliothecarius [SEP] place of death
Anastasius Bibliothecarius
Anastasius Bibliothecarius or Anastasius the Librarian (c. 810 – c. 878) was "bibliothecarius" (literally "librarian") and chief archivist of the Church of Rome and also briefly an Antipope. 
Early life.
He was a nephew of Bishop Arsenius of Orte, who executed important commissions as Papal legate. Anastasius learned the Greek language from Eastern Roman monks and obtained an unusual education for his era, such that he appears to be the most learned ecclesiastic of Rome in the 9th century.
is part of the scientific discussion on the place of the ichirgu-boil and the kavhan in the administration of the First Bulgarian Empire. The starting point of those discussions is that there were one kavhan and one ichirgu-boil at the same time and that the kavhan is the higher office. The different views on the functions of Peter comes from the different interpretation of the historical sources (the letters of Pope John VIII, the notes of the Cividale gospel and the story of Anastasius Bibliothecarius about the Council of Constantinople).