Klaus Rohde, Chris Hefford, John T. Ellis, Peter R. Baverstock, Alan M. Johnson, Nikki A. Watson, Sabine Dittmann,
Contributions to the phylogeny of platyhelminthes based on partial sequencing of 18S ribosomal DNA International Journal for Parasitology. ,vol. 23, pp. 705- 724 ,(1993) ,
10.1016/0020-7519(93)90067-9