Preface.- Semi-quasihomogeneous systems of ordinary differential equations.- 2. The critical case of purely imaginary kernels.- 3. Singular problems.- 4. The inverse problem for the Lagrange theorem on the stability of equilibrium and other related problems.- Appendix A. Nonexponential asymptotic solutions of systems of functional-differential equations.- Appendix B. Arithmetic properties of the eigenvalues of the Kovalevsky matrix and conditions for the nonintegrability of semi-quasihomogeneous systems of ordinary di erential equations.- Bibliography.