@book { ZumkonomischenProblemderAgglomerationsgrsse,
    title = "Zum ökonomischen Problem der Agglomerationsgrösse",
    author = "Max {Zumstein}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1069624"
}