Joseph Nelson Rose
The Cactaceae: Descriptions and Illustrations of Plants of the Cactus Family; Volume 1
Nathaniel Lord Britton
List of Plants Collected by Dr. Edward Palmer in 1890 in Lower California and Western Mexico, At: 1. La Paz, 2. San Pedro Martin Island, 3. Raza Islan
George VaseyThe Cactaceae: Descriptions and Illustrations of Plants of the Cactus Family; Volume 3
Nathaniel Lord Britton