@book { DermittelalterlicheundderneuzeitlicheWalther,
    title = "Der mittelalterliche und der neuzeitliche Walther",
    author = "Thomas {Bein}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1103131"
}