Loeblich, A. R., Douglass, R. C., Cole, W. S., Tappan, H., & Reichel, M. (1964). Part C, Protista 2, vol. 1 & 2, v.2, Ch.5, p. 511-604. Treatise on Invertebrate Paleontology. https://doi.org/10.17161/dt.v0i0.5094