Firms and the Gender Wage Gap: A Comparison of Eleven Countries (with Marco G. Palladino, Antoine Bertheau, Alexander Hijzen, Astrid Kunze, Cesar Barreto, Dogan Gülümser, Anne Sophie Lassen, Salvatore Lattanzio, Benjamin Lochner, Stefano Lombardi, Jordy Meekes, Balazs Murakozy, and Oskar Nordström Skans)