@book { OperfrKinder,
    title = "Oper für Kinder",
    subtitle = "Zur Gattung und ihrer Geschichte- Mit einer Fallstudie zu Wilfried Hiller",
    author = "Andrea {Grandjean-Gremminger}",
    year = "2008",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1103693"
}