Linguistic note: The obvious reference in these verses is to the Bible. In describing the Bible, the Book of Mormon text uses the term "book." While this term certainly correctly connotes to the modern reader the meaning of the text, it is unclear what the term would have been that Nephi understood from the angel. Nephi would certainly have been familiar with the term scrolls, and perhaps there was a collective term for the accumulated writings of the law and prophets. Nevertheless, our text uses none of those terms, but rather the more modern "book." This is another indication that in the process of translation, there is a shift in ideas and terminologies based upon Joseph's understanding and world. The word "book" is definitely not out of place, it is simply not likely to have the precise meaning that the word on the gold plates would have had.
Historical note: When the angel is describing the Bible to Nephi, he helps Nephi understand what it is by relating it to a known sacred record, the brass plates. The interesting note in verse 23 is that the Bible "is a record like unto the engravings which are upon the plates of brass, save there are not so many." The clear statement is that the brass plates contain more information that does the Bible. While we have little of the brass plates in the Book of Mormon, we have enough to know that there are prophets included in the brass plates, such as Zenos and Zenock, which are not present in the Bible.