2 literature references for Erylus euastrum aspidodiscus Topsent, 1928:

Author: Van Soest, R.W.M.
Year: 2001
Title: Porifera, in: Costello, M.J. et al. (Ed.) (2001).
Source: European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels, 50:
Author: Topsent, E.
Year: 1928
Title: Spongiaires de l’Atlantique et de la Méditerranée provenant des croisières du Prince Albert ler de Monaco.
Source: Résultats des campagnes scientifiques accomplies par le Prince Albert I. Monaco 74:1-376, pls I-XI.