@book { AufbauUmbauNeubau,
    title = "Aufbau – Umbau – Neubau",
    author = "Silke {Flegel} and Frank {Hoffmann}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1105298"
}