Paiva, T. D. S., and I. D. Da Silva–Neto. “Description of Parentocirrus Brasiliensis sp. N. (Ciliophora: Spirotrichea), a New Ciliate Protist Present in Activated Sludge”. Zootaxa, vol. 504, no. 1, May 2004, pp. 1–10, doi:10.11646/zootaxa.504.1.1.