 Canonical perturbation theory of Anosov systems and regularity results for the Livsic cohomology equation by Rafael de la Llave and others (1986)

Annals of Mathematics 123(3), 537–611. DOI: doi.org/10.2307/1971334 . Official publisher page verifies all three exact names. Full article, distinct from the existing 1985 Bulletin announcement. Cited for canonical perturbation and regularity of the Livsic cohomology equation; Sharp’s 2025 primary paper provides accessible contextual discussion.