@book { StudienzurGeschichtePapstEugensIII11451153,
    title = "Studien zur Geschichte Papst Eugens III. (1145-1153)",
    author = "Michael {Horn}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1080033"
}