If you are looking for 5th-grade Russian language solutions (GDZ), the most standard textbooks for that era and curriculum level are authored by or M.M. Razumovskaya . Popular Alternatives for 5th Grade GDZ

: Rules for unstressed vowels, roots with alternating vowels ( ), and spelling after sibilants.

Derzhavin, GR Poems. In Russian. Стихотворения - eBay

Based on the search results, there is no evidence of a widely recognized Russian language textbook for the 5th grade authored by "G. Derzhavin" in 2007. This name is most commonly associated with the classical poet , whose poems are often studied in literature classes rather than used as a primary grammar textbook.

Regardless of the textbook, a typical 5th-grade curriculum in Russia covers:

: Another common curriculum choice with digital answer keys available on GDZ.ru. Key Topics Covered in 5th Grade

Could you double-check the or the exact title on the book's cover? It’s possible the name belongs to a less common workbook editor or a specific regional program.