Nyffeler R., Phylogenetic relationships in the cactus family (Cactaceae) based on evidence from trnK/matK and trnL–trnF sequences, American Journal of Botany, 2002, 89(2):312-326, doi: 10.3732/ajb.89.2.312
An analysis of plastid trnK/matK and trnL–trnF sequences compares major Cactaceae lineages. It discusses the circumscription of traditional groups, the position of Blossfeldia and separation of Castellanosia from Browningia. Resolution of some generic relationships remains limited.