@book { konomikPhysikMathematik,
    title = "Ökonomik – Physik – Mathematik",
    author = "Volker {Wellhöner}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1093843"
}