There is a word that describes books that are not part of the twenty -four holy writings that make up the Tanach. This is called the "Apocrypha", which means, outside.
A perfect example of a book of the Apocrypha, would be ספר החשמונאים, also known as, "The Book of the Maccabees." I actually took a course on this book during my Yeshiva days at the Hebrew Theological College in Skokie, Illinois.
The book primarily discusses the war strategy of the Maccabees and how they were able to defeat the powerful Greek armies. They utilized the caves near Modiin and relied on swift surprise attacks mostly at night. Obviously, the miraculous victory was thanks to Hashem. But the way they went about it, with precision planning and intelligence, was very impressive.
The sages of Israel evaluated this book and did not feel that it contained רוח הקודש, so it did not become a book of Tanach. We are not really sure who the author was but we assume it was a devout Jew writing about the revolt and wars.
Books that made it as part of the Tanach with difficulty, were שיר השירים and קהלת, and even יחזקאל that seemed to have some discrepancies with the Torah. The Song of Songs and Ecclesiastes made it because of the specialness of King Solomon and his wisdom.