@book { unlearninghierarchy,
    title = "unlearning hierarchy",
    author = "Daniel {Vonier} and Lennart {Keil} and Tim {Höttges}",
    year = "2022",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1219160"
}