1. Allen , G. 1882 The Colours of Flowers
2. Discussion on the Vascular Structure of Seedlings;Anonymous;New Phytologist,1906
3. The Origin of Flowering Plants;Benson;New Phytologiat,1904
4. Contributions to the Embryology of the Amentiferee. Part Ii;Benson;Carpinus Betulus. Trans. Linn. Soc. London, 2nd ser. Bot.,1906
5. Phylogeny and Taxonomy of the Angiosperms;Bessey;Bot. Oca.,1897