Yanoski, De l'abolition de l'esclavage ancien au moyen age et de sa transformation en servitude de la glebe (Wallon and Yanoski had jointly composed a memoir to compete for a prize offered by the Academy of Moral and Political Sciences in 1837; Wallon's portion of the memoir became the foundation of his Histoire de l'esclavage dans l'antiquite above mentioned; Yanoski's part, the expansion of which was prevented by his early death, was posthumously published in 1860; it is no more than a slight sketch); Benjamin Gubrard, Prolegomenes au Polyptyque d'Irminon (1844); Fustel de Coulanges, Histoire des institutions politiques de l'ancienne France (2nd ed., 1877), and Recherches sur quelques problemes d'histoire (1885) (the latter work contains an admirable discussion of the whole subject of the colonatus, founded throughout on the original texts); Stubbs, Constitutional History of England (3 vols., 1874-1878).