What is the GP winner with a place of genk, with race winners ben adriaenssen / ben van den bogaart?
CREATE TABLE "2013" (
  "date" text,
  "place" text,
  "race_winners" text,
  "gp_winner" text,
  "source" text
);
SELECT "gp_winner" FROM "2013" WHERE "place"='genk' AND "race_winners"='ben adriaenssen / ben van den bogaart';