References
- Gray's Structural Botany 241 241
- Contributions to the Natural History of the Flower . Journ. Linn. Soc. Lond., Botany , xxx 55 – 55 .
- Contributions to the Natural History of the Flower . Journ. Linn. Soc. Lond., Botany , xxx 57 – 57 .
- 1888 . Proc. Acad. Nat. Sci. Philad. Nov. , 27 : 394 – 394 .
- Goebel . 1893 . Pflanzen-biologische Schilderungen . Marburg , ii : 363 – 363 . Theil, 2 Lief.