1956-59 Soviet Drifting Ice Station NP-6: Collection of 27 covers, postcards and postal stationery items related to Drifting Ice Station North Pole 6, drifting 8650 km, with official mail, radio mail, picture cards, nice illustrations and many types of cancellations. (Image)

19551956 Soviet Drifting Ice Stations NP-5: Six covers (up to last day (8.10.56) cover to Germany), three photocopies of photographs from the station and some information about cancellations etc. of the 3600 km drift.