CREATE TABLE table_30105 ("Series #" FLOAT, "Season #" FLOAT, "Title" TEXT, "Written by" TEXT, "Original air date" TEXT, "U.S. viewers  ( millions ) " TEXT)

who were the writers of the episode that had 5.56 millions of north american viewers?
SELECT "Written by" FROM table_30105 WHERE "U.S. viewers (millions)" = '5.56'
SELECT "Written by" FROM "table_30105" WHERE "U.S. viewers (millions)" = '5.56'