What were the dates administered in the Survey USA poll source where Republican Christopher Reed received 37%?
CREATE TABLE "opinion_polling_for_the_united_states_se" (
  "poll_source" text,
  "dates_administered" text,
  "democrat_tom_harkin" text,
  "republican_christopher_reed" text,
  "lead_margin" real
);
SELECT "dates_administered" FROM "opinion_polling_for_the_united_states_se" WHERE "poll_source"='survey usa' AND "republican_christopher_reed"='37%';