@book { Machihnglcklich,
    title = "Mach ihn glücklich",
    author = "Jan {van Amstel}",
    year = "2012",
    publisher = "dotbooks Verlag",
    address = "München, Deutschland",
    doi = "10.3239/9783943835403",
    url = "https://m.dotbooks.de/document/196014"
}