@book { SigmundFreudsMassenpsychologieundIchAnalyse,
    title = "Sigmund Freuds ,,Massenpsychologie und Ich-Analyse",
    author = "Christoph {Egen}",
    year = "2006",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638451468",
    url = "https://www.hausarbeiten.de/document/48430"
}