What is the date of the game where the vistor team was the Knicks and more than 18,165 were in attendance?
CREATE TABLE "april" (
  "date" text,
  "visitor" text,
  "score" text,
  "home" text,
  "leading_scorer" text,
  "attendance" real,
  "record" text
);
SELECT "date" FROM "april" WHERE "visitor"='knicks' AND "attendance">'18,165';