330제 282번, of which가 가리키는 것

The history we can know, the history we can learn and study, is, therefore, something much less comprehensive than history considered as the sum of all past events.
It is recorded history.
It includes only those things the memory of which has survived and is still available today.
여기서 of which가 무엇을 가리키는지 잘 모르겠어요ㅠㅠ