@book { UnequalFriendship,
    title = "Unequal Friendship",
    author = "Antoni {Mączak}",
    year = "2017",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-02368-8",
    url = "https://www.peterlang.com/document/1067764"
}