Citing the Stylonychia lemnae genome:

Ref: 24951568: Aeschlimann, S. H., Jönsson, F., Postberg, J., Stover, N. A., Petera, R. L., Lipps, H. J., Nowacki, M., & Swart, E. C. (2014). The draft assembly of the radically organized Stylonychia lemnae macronuclear genome. Genome biology and evolution, 6(7), 1707–1723. https://doi.org/10.1093/gbe/evu139