BioStor
 | La fauna de la Republica Argentina. E L Holmberg (1898) Segundo censo nacional : 477-602 |
 | 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 |
 | Muhlenberg on plants collected in the District of Columbia region about 1809 W L Mcatee (1922) Proceedings of The Biological Society of Washington 35: 63-71 |
 | The genera of Caprifoliaceae in the southeastern United States I K Ferguson (1966) Journal of the Arnold Arboretum 47: 33-59 |
 | 1St Flowering Dates For Spring blooming Plants Of The Washington, Dc, Area For The Years 1970 To 1983 S G Shetler and S K Wiser (1987) Proceedings of The Biological Society of Washington 100: 993-1017 |