@book { DieSPDunddieWiedervereinigung198990,
    title = "Die SPD und die Wiedervereinigung 1989/90",
    author = "Daniel {Eckert}",
    year = "2008",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640169856",
    url = "https://www.hausarbeiten.de/document/115468"
}