3 literature references:

Author: Webb,C.J. et al.
Year: 1988
Title:
Source: Flora of New Zealand Vol IV
Author: Stace,C.
Year: 1991
Title:
Source: New Flora of the British Isles.Cambridge Univ.Press
Author: Jessop,J. & Toelken,H.R.(Eds.)
Year: 1986
Title:
Source: Flora of South Australia, Part 2.