Kirchoff, Bruce K., Evelin Pfeifer, and Rolf Rutishauser. 2008. “Plant Structure Ontology: How Should We Label Plant Structures With Doubtful or Mixed Identities?”. Zootaxa 1950 (1). Auckland, New Zealand:103–122. https://doi.org/10.11646/zootaxa.1950.1.10.