suchen [und] SGB OA 21-[123][0123456789][0123456789][0123456789]* or OA 21-4[012345678][0123456789][0123456789]* or OA 21-49[012345678][0123456789]* or OA 21-499[0123456789]* or OA 21-0[123456789][0123456789][0123456789]* or OA 21-00[123456789][0123456789]* or OA 21-000[123456789]*