@book { TertirspracherwerbEinberblick,
    title = "Tertiärspracherwerb – Ein Überblick",
    author = "Kathleen {Fritzsche}",
    year = "2009",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640322299",
    url = "https://www.hausarbeiten.de/document/125931"
}