@book { GermansinTonga,
    title = "Germans in Tonga",
    author = "James N. {Bade}",
    year = "2014",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-04220-7",
    url = "https://www.peterlang.com/document/1048033"
}