Enoch - And there was in it †four† hollow places, deep and wide and very smooth. †How† smooth are the hollow places and deep and dark to look at.
Gg 

Notes

The book of Enoch is not part of the canonical scriptures (The Bible) we know today and we don't know how accurate it is.

Some belive while Enoch is not inspired by God that it still serves as a historical book on the time before the flood. It's also quoted in the New Testament in Jude 1:14-15.

Because of this I wanted to include this book for historical reasons.

I would recommend reading the Bible first and foremost as it should be your foundation. Then if you are intrested you can take a look at the book of Enoch.