Glossary of Plant Systematics (1st ed.) by Simpson (2006)
- Referring to the presence and number of mirror-image planes of symmetry.
Glossary of "Life (9th ed.)" by Sadava et al. (2011)
- Pertaining to an attribute of an animal body in which at least one plane can divide the body into similar, mirror-image halves. (See bilateral symmetry, radial symmetry.)
- Simpson, M. G. 2006. Plant Systematics. -xi + 590 pp. Elsevier Academic Press, Oxford.
- Sadava, D., Hillis, D. M., Heller, H. C. & Berenbaum, M. R. 2011. Life: The Science of Biology, 9th ed. -xliv + 1266 pp. Sinauer Associates, Inc., Sunderland.