@book { DerIndependentSystemOperator,
    title = "Der Independent System Operator",
    subtitle = "Ein neues institutionelles Design für Netzbetreiber?",
    author = "F. J. {Säcker}",
    year = "2007",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1103635"
}