@book { TheoretischeGrundlagenderPositivenPsychologie,
    title = "Theoretische Grundlagen der Positiven Psychologie",
    author = "Sebastian {Stern}",
    year = "2014",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    url = "https://www.hausarbeiten.de/document/271600"
}