``Reduction of polynomial Hamiltonians by the construction of
formal integrals."  Palaci\'an,~J. and Yanguas,~P.
{\sl Nonlinearity} {\bf 13} (2000) pp. 1021--1054.

``Reduction of polynomial planar Hamiltonians with quadratic
unperturbed part." Palaci\'an,~J. and Yanguas,~P.
{\sl SIAM Review} {\bf 42} (2000) pp. 671--691.

``Generalized normal forms for polynomial vector fields."
Palaci\'an,~J. and Yanguas,~P.
{\sl Journal des Math\'ematiques Pures et Appliqu\'ees} (2000), accepted,
25 pp.