1. Evolution of the leaf forms through the ages explained by successive retardation;Asama,1960
2. Evolution of Shansi flora and origin of simple leaf;Asama,1962
3. Permian plants from Phetchabun, Thailand and problems of floral migration from Gondwanaland;Asama;Bulletin of the National Science Museum,1966
4. Permian climatic cooling in the Canadian Arctic;Beauchamp,1994
5. Sun and shade leaves in two Jurassic species of Pteridosperms;Barbacka;Review of Palaeobotany and Palynology,1998