@book { Innecessariisunitas,
    title = "«In necessariis unitas»",
    author = "Wim de {Boer} and Peter-Ben {Smit}",
    year = "2012",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-01890-5",
    url = "https://www.peterlang.com/document/1047385"
}