@book { ZweckadquateGewinnermittlungsregeln,
    title = "Zweckadäquate Gewinnermittlungsregeln",
    author = "Silvia {Hettich}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1101820"
}