What was the original air date of the episode written by michael glassberg?
CREATE TABLE "table1_26866299_1" (
  "series_num" real,
  "episode_num" real,
  "title" text,
  "director" text,
  "writer" text,
  "original_airdate" text
);
SELECT "original_airdate" FROM "table1_26866299_1" WHERE "writer"='Michael Glassberg';