@book { TheCivilAdministrationofEasternTerritories19191920,
    title = "The Civil Administration of Eastern Territories (1919–1920)",
    subtitle = "The Reasons for the Failure of Piłsudski’s Federation Idea",
    author = "Joanna {Gierowska-Kałłaur}",
    year = "2022",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/b19743",
    url = "https://www.peterlang.com/document/1284929"
}