@book { TandemlearningontheInternet,
    title = "Tandem learning on the Internet",
    subtitle = "Learner interactions in virtual online environments (MOOs)",
    author = "Markus {Kötter}",
    year = "2002",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Allemagne",
    url = "https://www.peterlang.com/document/1094196"
}