what is the river whose source is thohoyandou and has it's mouth located in olifants river ?
SELECT DISTINCT var_uri where brack_open var_uri dbo_source dbr_Thohoyandou sep_dot var_uri dbo_riverMouth dbr_Olifants_River_ attr_open Limpopo attr_close sep_dot var_uri a dbo_River brack_close