2 literature references for Piptadenia opacifolia Ducke:

Author: Ducke,A.
Year: 1949
Title:
Source: Bol.Tecn.Inst.Agron.N.18:1-248 Notas Flora Neotropica-II:Ama
Author: Macbride,J.F.
Year: 1943
Title:
Source: Publ.Field Mus.Nat.Hist.,Bot.Ser.13(3/1):1-506 Leguminosae