@book { StudienzurSprachederlettischenVolkslieder,
    title = "Studien zur Sprache der lettischen Volkslieder",
    author = "Rainer {Eckert}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1102913"
}