@book { AnalyseundKritikderUmweltmanagementsysteme,
    title = "Analyse und Kritik der Umweltmanagementsysteme",
    author = "Gernot-Rüdiger {Engel}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1136183"
}