1. Babcock, E. B. andH. M. Hall, 1924.Hemizonia congesta, a genetic, ecologic, and taxonomic study of the hay-field tarweeds. Univ. Calif. Publ. Bot., 13, no. 2, 15?100 (cf. also subHall, H. M.).
2. Berry, E. W., 1920. Palaeobotany: A sketch of the origin and evolution of flora's. Ann. Rep. Smithson. Inst. 1918 (1920), 289?407 (esp. fig. 26).
3. ?, 1932. The story of fossil plants. Brooklyn Botanic Garden Record, 21, 209?237.
4. Bessey, Chas. E., 1897. The Phylogeny and Taxonomy of the Angiosperms. Bot. Gaz., 24, 145?178.
5. 1909. The phyletic idea in Taxonomy. Science, Jan. 15, 10 p.