Plant systematics . 388 p. Lawrence, George H.M. 1951. Taxonomy of vascular plants . 823 p. Porter, C.L. 1967. Taxonomy of flowering plants .
Vascular plant systematics .
891 p. Rendle, Alfred B. 1930. The classification of flowering plants. Volume I. Gymnosperms and monocotyledons . Cambridge University Press, London, England. The classification of flowering plants.