 Yehuda Bauer was similarly condemnatory, questioning how an institute such as Harvard could award a doctorate for a work which so "slipped through the filter of critical scholarly assessment".Bauer also suggested that Goldhagen lacked familiarity with sources not in English or German, which thereby excluded research from Polish and Israeli sources writing in Hebrew, among others, all of whom had produced important research in the subject that would require a more subtle analysis.Bauer also argued that these linguistic limitations substantially impaired Goldhagen from undertaking broader comparative research into European antisemitism, which would have demanded further refinements to his analysis.