@book { Internationalmigrationduringthe19thcentury,
    title = "International migration during the 19th century",
    author = "Malte {Wagenknecht}",
    year = "2007",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638781008",
    url = "https://www.hausarbeiten.de/document/73587"
}