list the leaders of all the cities through which the view of haarlem from the northwest river flows ?
SELECT DISTINCT var_uri where brack_open dbr_View_of_Haarlem_from_the_Northwest,_with_the_Bleaching_Fields_in_the_Foreground dbp_city var_x sep_dot var_x dbo_leaderName var_uri sep_dot var_x a dbo_City brack_close