“Forced Labour, Servitude and Slavery in Europe According to the Productive Sectors: Critical Analysis of the Scope of the Case Law of Article 4 of the European Convention on Human Rights”. UNIVERSITAS. Revista De Filosofía, Derecho Y Política, no. 25, Jan. 2017, pp. 90-138, https://e-revistas.uc3m.es/index.php/UNIV/article/view/3558.