@book { Diequivalenzstrung,
    title = "Die Äquivalenzstörung",
    subtitle = "Ein Beitrag zur Lehre von der Geschäftsgrundlage",
    author = "Philipp {Härle}",
    year = "1995",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1116219"
}