Equivariant harmonic maps between manifolds with metrics of ( p , q ) -signature Andrea Ratto — 1989 Annales de l'I.H.P. Analyse non linéaire
Existence and non-existence results for harmonic maps between spheres Valter Pettinati; Andrea Ratto — 1990 Annali della Scuola Normale Superiore di Pisa - Classe di Scienze
SO(2) invariant minimal and constant mean curvature surfaces in 3-dimensional homogeneous spaces. Renzo Caddeo; Paola Piu; Andrea Ratto — 1995 Manuscripta mathematica