list sports managers who managed club deportivo el nacional and ethnikos piraeus f . c . ?
SELECT DISTINCT var_uri where brack_open var_uri dbo_managerClub dbr_Club_Deportivo_El_Nacional sep_dot var_uri dbp_managerclubs dbr_Ethnikos_Piraeus_F.C sep_dot sep_dot var_uri a dbo_SportsManager brack_close