What track has a 250 cc of sito pons?
CREATE TABLE "winners_of_the_yugoslavian_motorcycle_gr" (
  "year" real,
  "track" text,
  "250_cc" text,
  "500_cc" text,
  "report" text
);
SELECT "track" FROM "winners_of_the_yugoslavian_motorcycle_gr" WHERE "250_cc"='sito pons';