BioStor
 | Sixth list of additions to the flora of Washington, D.C. vicinity. With descriptions of new species varieties by Edward L. Greene, Alvah A. Eaton, and the author E S Steele (1901) Proceedings of The Biological Society of Washington 14: 47-86 |
 | The vascular flora of three wildlife refuges in Cameron Parish, Louisiana B E Dutton and R D Thomas (1990) Phytologia 68: 333-362 |