1. Bozeman, J. R. 1971 — A sociologic and geographic study of the sand ridge vegetation in the coastal plain of Georgia. Ph.D. Dissertation, U.N.C. Botany Department, Chapel Hill. 216 pp.
2. Ellenberg, H. 1950 — Landwirtschaftliche Pflanzensoziologie, Vol. I, Ackerunkrautgemeinschaften als Zeiger für Klima und Boden. Ulmer, Ludwigsburg, 141 p.
3. Goodall, D. W. 1969 — A procedure for recognition of uncommon species combinations in sets of vegetation samples.Vegetatio 18: 19–35.
4. Leith, H. 1968 — Continuity and discontinuity in ecological gradients and plant communities.Botanical Review 34, 291–302.
5. Lieth, H. 1969 — in press. Mathematical modeling for ecosystem analyses, UNESCO Symposium on the Productivity of Forest Ecosystems of the World. Brussels, October 1969.