BioStor
 | June 5th (1860) Proceedings of The Academy of Natural Sciences of Philadelphia 12: 199-201 |
 | Kansas Aphididae, with catalogue of North American Aphididae, and with host-plant list, part II Sanborn (1906) Kansas University Science Bulletin 3: 225-275 |
 | A second supplement to the flora of Barro Colorado Island, Panama P C Standley (1930) Journal of the Arnold Arboretum 11: 119-129 |
 | The genera of Lactuceae (Compositae) in the southeastern United States B S Vuilleumier (1973) Journal of the Arnold Arboretum 54: 42-93 |
 | 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 |