@book { ErichHeintelMndigerMenschundchristlicherGlaube,
    title = "Erich Heintel: Mündiger Mensch und christlicher Glaube",
    author = "Stephan {Haltmayer} and Waltraud {Heintel}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1097053"
}