1. Circular causal systems in ecology;Hutchinson,1948
2. A non-linear differential-difference equation of growth;Cunningham,1954
3. The existence of periodic solution of ƒ′(x)=−aƒ(x−1){1+ƒ(x)};Stephen Jones,1962
4. On the stability of a periodic solution of a differential delay equation;Kaplan,1975
5. Stability and Complexity in Model Ecosystems;May,1973