which subsidiary of klm serves both rotterdam the hague airport and amsterdam airport schiphol ?
select distinct var_uri where brack_open dbr_KLM dbo_subsidiary var_uri sep_dot var_uri dbo_targetAirport dbr_Rotterdam_The_Hague_Airport sep_dot var_uri dbo_targetAirport dbr_Amsterdam_Airport_Schiphol sep_dot brack_close