The fact is that if you were speaking English before about a thousand years ago, beek is exactly what you would have said for more than one book.
사실, 여러분이 대략 1,000년 전에 영어를 썼다면, 여러 권의 책을 말할때  여러분은 'beek'이라고 말하는 게 맞았을거에요.