@book { IndianischfrAnfnger,
    title = "Indianisch für Anfänger",
    subtitle = "Ein Au-pair-Mädchen auf Pine Ridge",
    author = "Kerstin {Groeper}",
    year = "2016",
    publisher = "hey! publishing",
    address = "München, Deutschland",
    url = "https://www.heypublishing.com/document/317461"
}