What are the serial numbers for the locomotives of Class 4-8-4 — oooooooo — northern?
CREATE TABLE "4_8_4" (
  "class" text,
  "wheel_arrangement" text,
  "fleet_number_s" text,
  "manufacturer" text,
  "serial_numbers" text,
  "year_made" text,
  "quantity_made" text,
  "quantity_preserved" text,
  "year_s_retired" text
);
SELECT "serial_numbers" FROM "4_8_4" WHERE "class"='4-8-4 — oooooooo — northern';