@book { CortesiaPolitesseCortesa,
    title = "Cortesia – Politesse – Cortesía",
    author = "Gudrun {Held} and Uta {Helfrich}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1107550"
}