@book { FehlinvestitionenundihrePrfung,
    title = "Fehlinvestitionen und ihre Prüfung",
    author = "Klaus {Rockel}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1072181"
}