What were the dates administered when the lead margin was smaller than 39 with Republican Christopher Reed at 37% and Democrat Tom Harkin at 53%?
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 "lead_margin"<39 AND "republican_christopher_reed"='37%' AND "democrat_tom_harkin"='53%';