@book { Selbstwertgefhlsteigern,
    title = "Selbstwertgefühl steigern",
    author = "Lukas {Rick}",
    year = "2017",
    publisher = "humboldt",
    address = "Hannover, Deutschland",
    url = "https://schluetersche.openpublishing.com/document/403251"
}