How find the location of a table or index blocks

( tablespace, datafiles and block_ids ) 

SELECT e.tablespace_name,d.file_name,e.block_id
  FROM dba_extents e, dba_data_files d 
  where owner = 'DMITRI' and segment_name = 'MY_TABLE'
  and e.file_id = d.file_id;
TABLESPACE_NAME FILE_NAME BLOCK_ID
1 USERS /dev_oradata4/dwstg/users04.dbf 4485
2 USERS /dev_oradata4/dwstg/users01.dbf 2245
3 USERS /dev_oradata4/dwstg/users02.dbf 1989