@book { GefhrdungexistierenderKundenbeziehungen,
    title = "Gefährdung existierender Kundenbeziehungen",
    author = "Sonja {Klose}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1103845"
}