@book { Stressfreiin10Minuten,
    title = "Stressfrei in 10 Minuten",
    author = "Heike {Höfler}",
    year = "2010",
    publisher = "humboldt",
    address = "Hannover, Deutschland",
    url = "https://schluetersche.openpublishing.com/document/403374"
}