@book { DergeometrischeEntwurfderHagiaSophiainIstanbul,
    title = "Der geometrische Entwurf der Hagia Sophia in Istanbul",
    subtitle = "Bilder einer Ausstellung",
    author = "Volker {Hoffmann}",
    year = "2005",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1098882"
}