@book { Pourquoiapprendredeslangues,
    title = "Pourquoi apprendre des langues ?",
    author = "Gerhard {Bach} and Gisèle {Holtzer}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1101498"
}