2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/121438We give a survey on the Weierstrass representations of surfaces in three- and four-dimensional spaces, their applications to the theory of the Willmore functional and on related problems of spectral theory of the two-dimensional Dirac operator with periodic coefficients.82 pages, minor additionsDifferential Geometrytext