Which Country has a FIS Nordic World Ski Championships of 1948, 1950?
CREATE TABLE "men_s_nordic_combined" (
  "winner" text,
  "country" text,
  "winter_olympics" text,
  "fis_nordic_world_ski_championships" text,
  "holmenkollen" text
);
SELECT "country" FROM "men_s_nordic_combined" WHERE "fis_nordic_world_ski_championships"='1948, 1950';