@book { DemographicAspectsoftheEarlyModernTimes,
    title = "Demographic Aspects of the Early Modern Times",
    author = "Walter {Letsch}",
    year = "2017",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    doi = "10.3726/b11232",
    url = "https://www.peterlang.com/document/1055663"
}