W.L.Wagner (A.Gray) 1999 - Wagner WL, Fletcher RA, Shannon RK (1999) Another Look at Hymenoxys Subgenus Plummera (Asteraceae: Heliantheae: Gaillardiinae) from Arizona and New Mexico. Brittonia 51(1): 79-86. doi: 10.2307/2666562.
There is no corrections for Hymenoxys ambigens var. floribunda yet.