2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/52269This publication is an exercise which extends to two variables the Christoffel's construction of orthogonal polynomials for potentials of one variable with external sources. We generalize the construction to biorthogonal polynomials. We also introduce generalized Schur polynomials as a set of orthogonal, symmetric, non homogeneous polynomials of several variables, attached to Young tableaux.latex poly.tex, 1 file, 33 pages [SPhT-T03/180], submitted to Commun. Math. Phys.http://www-spht.cea.fr/articles/T03/180 SPhT-T03/180High Energy Physics - TheoryMathematical Physicstext