Chapman, A. D. (2007): Numbers of Living Species in Australia and the World. Invertebrates. A Report for the Department of the Environment and Heritage. Australian Biodiversity Information Services. Ver en liña.
nih.gov
ncbi.nlm.nih.gov
Cameron, C. B.; Garey, J. R. e Swalla, B. J. (2000): "Evolution of the chordate body plan: new insights from phylogenetic analyses of deuterostome phyla" Proceedings of the National Academy of Sciences of the United States of America97 (9): 4469–74. Ver en liña