@book { Slowakei,
    title = "Slowakei",
    subtitle = "An der Kreuzung Europas",
    author = "Irina {Scherf} and Holger {Scherf} and Herbert {Strunz}",
    year = "2009",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1106848"
}