Sofia Petrovna works in a large publishing house in Leningrad. This is highly appropriate on several levels; literature and writers had always traditionally been held in great esteem in Russia, and there was at this time a huge literacy drive (ie in Russian) throughout the Soviet Union. This is a poster (c1924, details here) for a state publishing house with "books on all branches of knowledge". It depicts the famous bookshop Dom Knigi (House of the Book) in the former Singer sewing machine building (1902-4) on Nevsky Prospect.