BioStor
 | Notes on the genus Xolocotzia (Verbenaceae) H N Moldenke (1981) Phytologia 48: 390-392 |
 | A sixth summary of the Verbenaceae, Avicenniaceae, Stilbaceae, Chloanthaceae, Symphoremaceae, Nyctanthaceae, and Eriocaulaceae of the world as to valid taxa, geographic distribution and synonymy. Supplement 2 H N #moldenke (1982) Phytologia 52: 110-129 |
 | Systematics and Evolution of the Genus Petrea (Verbenaceae) Ricardo M Rueda (1994) Annals of the Missouri Botanical Garden 81: 610-652 |