@book { LaescrituracancillerescadeFernandoIIIAlfonsoXSanchoIVyFernandoIV,
    title = "La escritura cancilleresca de Fernando III, Alfonso X, Sancho IV y Fernando IV",
    author = "Leyre {Martín Aizpuru}",
    year = "2020",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    doi = "10.3726/b17453",
    url = "https://www.peterlang.com/document/1058910"
}