What Tournament did Silva Partner with Nicole Thijssen with Opponent in the final Nina Bratchikova & Frederica Piedade?
CREATE TABLE "doubles_18" (
  "date" text,
  "tournament" text,
  "surface" text,
  "partner" text,
  "opponent_in_the_final" text,
  "score" text
);
SELECT "tournament" FROM "doubles_18" WHERE "partner"='nicole thijssen' AND "opponent_in_the_final"='nina bratchikova & frederica piedade';