Russia-Pleskau, registered Soviet 60 Kopeck postal stationery envelope, with additional postage Mi number 10/11 y and 12 by, cancelled with stamp "PCKOB * K * 12 2 42" and "PCKOB * a * 12 2 42", overfranked, excellent condition, expertized by Dr. Rommerskirchen BPP, photographic finding by Robert Brunel VP (2025) "The condition is flawless."