Observational analysis of the well--correlated diffuse bands: 6196 and
  6614 \AA
  We confirm, using spectra from seven observatories, that the diffuse bands
6196 and 6614 are very tightly correlated. However, their strength ratio is not
constant as well as profile shapes. Apparently the two interstellar features do
not react in unison to the varying physical conditions of different
interstellar clouds.
