@book { PrinciplesofGrammarTheory,
    title = "Principles of Grammar Theory",
    subtitle = "edited by Theo Harden and Harald Weydt",
    author = "Theo {Harden}",
    year = "1995",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1116261"
}