@book { Affairesdepatrons,
    title = "Affaires de patrons",
    subtitle = "Villes et commerce transfrontalier au Sahel- Préface de Denis Retaillé",
    author = "Olivier {Walther}",
    year = "2008",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1104312"
}