what is the river whose source is cracăul negru river and has it's mouth located in bistrița ?
SELECT DISTINCT var_uri where brack_open var_uri dbo_source dbr_Cracăul_Negru_River sep_dot var_uri dbo_riverMouth dbr_Bistrița_ attr_open Siret attr_close sep_dot var_uri a dbo_River brack_close