We provide very general symmetrization theorems in arbitrary dimension and codimension, in products, warped products, and certain fiber bundles such as lens spaces, including Steiner, Schwarz, and spherical symmetrization and admitting density.
"Steiner and Schwarz symmetrization in warped products and fiber bundles with density." Rev. Mat. Iberoamericana 27 (3) 909 - 918, September, 2011.