which subsidiary of klm serves both groningen airport eelde and rotterdam the hague airport ?
select distinct var_uri where brack_open dbr_KLM dbo_subsidiary var_uri sep_dot var_uri dbo_targetAirport dbr_Groningen_Airport_Eelde sep_dot var_uri dbo_targetAirport dbr_Rotterdam_The_Hague_Airport sep_dot brack_close