Template:Hawkins et al., 1999
- Hawkins. J.A., White Olascoaga, L, Hughes, C.E., Contreras Jiménez, J.-L. R. & Mercado Ruaro, P. 1999. Investigation and documentation of hybridization between Parkinsonia aculeata and Cercidium praecox (Leguminosae:Caesalpinioideae). Plant Systematics and Evolution 216(1–2): 49–68. DOI: 10.1007/BF00985100