Agatha, S., & Strüder-Kypke, M. C. (2007). Phylogeny of the order Choreotrichida (Ciliophora, Spirotricha, Oligotrichea) as inferred from morphology, ultrastructure, ontogenesis, and SSrRNA gene sequences. European Journal of Protistology, 43(1), 37–63. doi:10.1016/j.ejop.2006.10.001