Sites like GDZ.ru or Skysmart often maintain older exercise databases under a "Previous Editions" or "Other Years" filter.
Key spelling rules for unstressed vowels and consonant clusters. gdz po russkomu jazyku klass baranov za 2007 god
Since the 2007 version is an older edition, it is often archived on specialized "Retro" or "Old Edition" sections of educational portals: Sites like GDZ