M. J.  Telford, Lockyer, A. E., Cartwright-Finch, C., och Littlewood, D. T. J., ?Combined large and small subunit ribosomal RNA phylogenies support a basal position of the acoelomorph flatworms?, Proceedings of the Royal Society B: Biological Sciences, vol 270, num 1519, ss 1077 - 1083, 2003.

I.  Ruiz-Trillo, Riutort, M., Littlewood, D. T. J., Herniou, E. A., och Baguna, J., ?Acoel flatworms: earliest extant bilaterian metazoans, not members of Platyhelminthes.?, Science, vol 283, ss 1919 - 1923, 1999.