1. A general bifurcation theorem;Cronin,1977
2. Cronin J., Bifurcation of periodic solutions, J. math. Analysis Applic. To be published.
3. Bifurcation from simple Eigenvalues;Crandall;J. funct. Analysis,1971
4. Loss of stability and bifurcation at a double Eigenvalue;McLeod;J. funct. Analysis,1973
5. Functional analysis, nonlinear differential equations and the alternative method;Cesari,1976