@book { Widerstandgesternundheute,
    title = "Widerstand – gestern und heute",
    author = "Heidi {Beutin} and Wolfgang {Beutin} and Ernst {Heilmann}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1106905"
}