CREATE TABLE table_28520 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( million ) " TEXT)

which production codes were written by andrew goldberg
SELECT "Production code" FROM table_28520 WHERE "Written by" = 'Andrew Goldberg'
SELECT "Production code" FROM "table_28520" WHERE "Written by" = 'Andrew Goldberg'