EU 4BB 1928 USSR

QTH - Kazan city (now UA4P).

Cover side. In the center of QSL is "Society "Friends of Radio" logo. Cyrilic letters "ODP" is acronim for this Society. Small Cyrilic letters above like "CCCP" stand for "USSR".

Back side. Small text block in top right corner for post service is a "stamp". Text states that QSL exchange is free of cost (inside the USSR), no any postal stamps are required. It is hard to belive but this rule worked since 1928 untill mid-70s!

Courtesy of RU3AX