@book { VladimirSolovevundFriedrichNietzsche,
    title = "Vladimir Solov’ev und Friedrich Nietzsche",
    author = "Urs {Heftrich} and Gerhard {Ressel}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1095697"
}