It really depends on what book you are referring to. :0)
I, for one, will only adhere to the words of the Holy Bible, in particular, the New Testament.
What makes the Holy Bible so amazing, is it is just as relevant today as it was 4,000 years ago, when the patriarchs first started to put "paper to pen". It is also important to note that there were works that were considered Scripture, by the ancient Hebrews, such as the Book of Jasher and Enoch, that are referenced in the Bible, but did not find a home there, even though they are far older and seem to be quite reliable.
The Old Testament is great for an over-all historical perspective on how the Almighty delt with the Hebrews and Israelites prior to the Old Covenant and the Israelites and Jews during the Old Covenant. It will also tell you about all those nations that interacted with Israel during this time.
The New Testament is about the approaching end of the Old Covenant and the Jews falling out of grace with God and no longer being His "chosen people".
The New Covenant is thus ushered in by Jesus the Christ, God's only begotten Son, and begins as soon as the Old Covenant ends in 70 A.D. - with the final destruction of The Temple in Jerusalem along with the destruction of the "great city" and most of Israel and Judea.
In A.D. 70 the New Covenant began and now everyone, both Jew and Gentile alike, are now welcomed to partake in Christ's masterful plan of salvation.
The Old and New Testament are simply fascinating and I believe they are inspired of God, on a spiritual, practical, and historical level.
So, at the end of the day, it would seem to me that the closer the writings and accounts are to the original "Source", the more accurate, reliable, and truthful they tend to be.