@book { KonsumentenzufriedenheitundBeschwerden,
    title = "Konsumentenzufriedenheit und Beschwerden",
    author = "Manfred {Bruhn}",
    year = "2018",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/b13617",
    url = "https://www.peterlang.com/document/1068215"
}