What june 21–22, 2011 polling has green smaller than 13?
CREATE TABLE "opinion_polls" (
  "polling_firm" text,
  "date_of_polling" text,
  "link" text,
  "liberal" real,
  "green" real
);
SELECT "polling_firm" FROM "opinion_polls" WHERE "green"<13 AND "date_of_polling"='june 21–22, 2011';