1. Ayyad, M. 1971 — A study of solar radiation on sloping surfaces at AlexandriaU.A.R. J. Bot., 14, 65–74.
2. Davis, P. H. 1951 — Cliff vegetation in the eastern Mediterranean.J. Ecol., 39, 63–93.
3. Geiger, R. 1957 — The Climate Near the Ground. Harvard press, Cambridge, Mass., 2nd ed., revised. pp. 494.
4. Kassas, M. 1952 — Habitat and plant communities in the Egyptian desert. I., Introduction.J. Ecol., 40, 342–351.
5. Kassas, M. 1953 — Landforms and plant cover in the Egyptian desert.Bull. Soc. Geogr. Egypte, 26, 193–205.