REFERENCES
- HALE , J. K. , 1965 , J. diff. Equations , 1 , 452 .
- HALE , J. K. , and INFANTE , E. F. , 1967 , Proc. Natn Acad. Sci. , 58 , 405 .
- KRASOVSKII , N. N. , 1963 , Stability of Motion ( Stanford , Calif . Stanford University Press ).
- †Communicated by the Author.