@book { PositiveLeadership,
    title = "Positive Leadership",
    subtitle = "Leading successfully with PERMA-Lead: The five keys to high performance",
    author = "Markus {Ebner}",
    year = "2020",
    publisher = "facultas",
    address = "Wien, Österreich",
    url = "https://campus-lizenzen.facultas.at/document/540564"
}