@book { RealConvergenceintheEuropeanUnion,
    title = "Real Convergence in the European Union",
    author = "Christian {Schmidt}",
    year = "1998",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/b13565",
    url = "https://www.peterlang.com/document/1068170"
}