Reference

P.W. Johnson, P.L. Donaghay, Eugene Small, J.M. Sieburth (1995): Ultrastructure and ecology of Perispira ovum (Ciliophora: Litostomatea): an aerobic, planktonic ciliate that sequesters the chloroplasts, mitochondria, and paramylon of Euglena proxima in a micro-oxic habitat – J. Euk. Microbiol. – 42: 323 - 335.