2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/197456We carry out the extension of the covariant Ostrogradski method to fermionic field theories. Higher-derivative Lagrangians reduce to second order differential ones with one explicit independent field for each degree of freedom.12 pages, ReVTeX; minor typos corrected; references updated; to appear in J. Phys. AHigh Energy Physics - Theorytext