Olson, Mark E.; Lomelí S., José A.; Cacho, N. Ivalú (2005). "Extinction threat in the Pedilanthus clade (Euphorbia, Euphorbiaceae), with special reference to the recently rediscovered E. conzattii (P. pulchellus)". American Journal of Botany. 92 (4): 634–641. doi:10.3732/ajb.92.4.634. ISSN0002-9122. PMID21652441.
Gucker, Corey L (2010). "Euphorbia esula". Fire Effects Information System, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Archived from the original on 20 May 2022. Retrieved 10 June 2019.
Olson, Mark E.; Lomelí S., José A.; Cacho, N. Ivalú (2005). "Extinction threat in the Pedilanthus clade (Euphorbia, Euphorbiaceae), with special reference to the recently rediscovered E. conzattii (P. pulchellus)". American Journal of Botany. 92 (4): 634–641. doi:10.3732/ajb.92.4.634. ISSN0002-9122. PMID21652441.
Gucker, Corey L (2010). "Euphorbia esula". Fire Effects Information System, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Archived from the original on 20 May 2022. Retrieved 10 June 2019.
Olson, Mark E.; Lomelí S., José A.; Cacho, N. Ivalú (2005). "Extinction threat in the Pedilanthus clade (Euphorbia, Euphorbiaceae), with special reference to the recently rediscovered E. conzattii (P. pulchellus)". American Journal of Botany. 92 (4): 634–641. doi:10.3732/ajb.92.4.634. ISSN0002-9122. PMID21652441.