@book { LaUninEuropeayelprincipiodesolidaridadTheEuropeanUnionandthePrincipleofSolidarity,
    title = "La Unión Europea y el principio de solidaridad / The European Union and the Principle of Solidarity",
    author = "Juan Carlos {Moreno Piñero} and Teresa {Freixes San Juan}",
    year = "2025",
    publisher = "Peter Lang Verlag",
    address = "Bruxelles, Belgium",
    doi = "10.3726/b22493",
    url = "https://www.peterlang.com/document/1512464"
}