Cialdella, A.M., L.M. Giussani, L. Aagesen, F.O. Zuloaga, O. Morrone. A Phylogeny of Piptochaetium (Poaceae: Pooideae: Stipeae) and Related Xenera Based on a Combined Analysis Including Trnl-f, Rpl16, and Morphology. Systematic Botany Vol 28, xineru 2003.