@book { SigmundFreudsTheoriederpsychosexuellenEntwicklung,
    title = "Sigmund Freuds Theorie der psycho-sexuellen Entwicklung",
    author = "Patrick {Gräbner}",
    year = "2009",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640443819",
    url = "https://www.hausarbeiten.de/document/136747"
}