what is the river whose source place is breisgau-hochschwarzwald and mouth place is waldshut ?
SELECT DISTINCT var_uri where brack_open var_uri dbo_sourcePlace dbr_Breisgau-Hochschwarzwald sep_dot var_uri dbo_mouthPlace dbr_Waldshut_ attr_open district attr_close sep_dot var_uri a dbo_River brack_close