@book { KalkulationenzurBioschweinehaltung,
    title = "Kalkulationen zur Bioschweinehaltung",
    author = "Michael {Omelko}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832452926",
    url = "https://m.diplom.de/document/220858"
}