Alves, F.M.A., Chícharo, L.M., Serrao, E. and Abreu, A.D. 2001. Algal cover and sea urchin spatial distribution at Madeira Island (NE Atlantic). Scientia Marina. 65, 4 (Dec. 2001), 383–392. DOI:https://doi.org/10.3989/scimar.2001.65n4383.