@book { DieHeilkraftderBume,
    title = "Die Heilkraft der Bäume",
    author = "Kurt {Allgeier}",
    year = "2012",
    publisher = "hey! publishing",
    address = "München, Deutschland",
    doi = "10.3239/9783942822282",
    url = "https://www.heypublishing.com/document/206745"
}