@book { AktiveGelassenheit,
    title = "Aktive Gelassenheit",
    subtitle = "Festschrift für Heinrich Beck zum 70. Geburtstag",
    author = "Eun {Kim} and Erwin {Schadel} and Uwe {Voigt}",
    year = "1999",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1088675"
}