Who won the FIS Nordic World Ski Championships in 1972?
CREATE TABLE "men_s_50_km" (
  "winner" text,
  "country" text,
  "winter_olympics" real,
  "fis_nordic_world_ski_championships" text,
  "holmenkollen" text
);
SELECT "winner" FROM "men_s_50_km" WHERE "fis_nordic_world_ski_championships"='1972';