2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/54727We sketch recent applications of the harmonic superspace approach for off-shell formulations of $(4,4)$, $2D$ sigma models with torsion and for constructing super KdV hierarchies associated with "small" and "large" $N=4$ superconformal algebras.12 pages, LaTeX, Talk given at the 10th International Conference on Problems Of Quantum Field Theory, Alushta (Crimea, Ukraine) 13-18 May 1996 (to be published in Proceedings)High Energy Physics - Theorytext