This photo, taken around the second half of 1975, was sent to ThereminWorld by Karl Grundstein of Riga, Latvia. He is a retired electronics engineer and designer of "classic type electronic organ ("Preludia")", which was manufactured in Riga's Musical Instruments plant for about 17 years. In this respect, he was a member of the All-Union electromusical instrument makers' coordination council. Every enterprise in the USSR involved in manufacturing any electromusical instrument delegated one person to this council to coordinate projects.
In addition to the 25-30 members, special honored delegates also attended the meetings. Leon Theremin was one such delegate. Mr. Grundstein writes:
The man sitting behind Mr. Grundstein is Vjacheslav Meshcherin, conductor of Moscow Radio's Electromusical Instrument Ensemble.
On the back of the photo next to the signatures is a date indicating the next meeting time.