Concise Bible Dictionary:

The form of ancient books was a long roll with a roller at each end. These rollers were held one in each hand and the book was unrolled from off the one and on to the other as the book was read; and this had to be reversed before the book could be read again. They were made of skins, and the writing was usually on one side only; to be written on both sides would show a full record (Ezek. 2:9-109And when I looked, behold, an hand was sent unto me; and, lo, a roll of a book was therein; 10And he spread it before me; and it was written within and without: and there was written therein lamentations, and mourning, and woe. (Ezekiel 2:9‑10); Rev. 5:11And I saw in the right hand of him that sat on the throne a book written within and on the backside, sealed with seven seals. (Revelation 5:1)). The form of a roll explains how a book could have several seals, a portion being rolled up and a seal attached; then another portion rolled up and another seal, like the seven-sealed book of Revelation.
By the ancient nations records were made on cylinders or slabs of stone, or on clay, which was then baked or sun-dried. Many such tablets have been found in the excavations made at Nineveh, Babylon and other places. When Ezra was at work on the city and temple of Jerusalem his opponents wrote to the king of Persia asking that “the book of the records” might be searched for corroboration of their assertion that Jerusulem had been rebellious (Ezra 4:1515That search may be made in the book of the records of thy fathers: so shalt thou find in the book of the records, and know that this city is a rebellious city, and hurtful unto kings and provinces, and that they have moved sedition within the same of old time: for which cause was this city destroyed. (Ezra 4:15)). The “book of the records” was doubtless a collection of stone or clay tablets. In some cases these have been found in such numbers as to form quite a library.
The word BOOK is used symbolically for what a book might contain, as prophecy or predictions. Ezekiel and John were told to eat the books presented to them (Ezek. 2:8-98But thou, son of man, hear what I say unto thee; Be not thou rebellious like that rebellious house: open thy mouth, and eat that I give thee. 9And when I looked, behold, an hand was sent unto me; and, lo, a roll of a book was therein; (Ezekiel 2:8‑9); Ezek. 3:1-31Moreover he said unto me, Son of man, eat that thou findest; eat this roll, and go speak unto the house of Israel. 2So I opened my mouth, and he caused me to eat that roll. 3And he said unto me, Son of man, cause thy belly to eat, and fill thy bowels with this roll that I give thee. Then did I eat it; and it was in my mouth as honey for sweetness. (Ezekiel 3:1‑3); Rev. 10:99And I went unto the angel, and said unto him, Give me the little book. And he said unto me, Take it, and eat it up; and it shall make thy belly bitter, but it shall be in thy mouth sweet as honey. (Revelation 10:9): Compare Jer. 15:1616Thy words were found, and I did eat them; and thy word was unto me the joy and rejoicing of mine heart: for I am called by thy name, O Lord God of hosts. (Jeremiah 15:16)). It is also symbolical of the records that are with man usually written in a book (Psa. 56:88Thou tellest my wanderings: put thou my tears into thy bottle: are they not in thy book? (Psalm 56:8); Dan. 7:1010A fiery stream issued and came forth from before him: thousand thousands ministered unto him, and ten thousand times ten thousand stood before him: the judgment was set, and the books were opened. (Daniel 7:10); Mal. 3:1616Then they that feared the Lord spake often one to another: and the Lord hearkened, and heard it, and a book of remembrance was written before him for them that feared the Lord, and that thought upon his name. (Malachi 3:16); Rev. 20:1212And I saw the dead, small and great, stand before God; and the books were opened: and another book was opened, which is the book of life: and the dead were judged out of those things which were written in the books, according to their works. (Revelation 20:12)).
Various books are mentioned in scripture which are not now in existence.
1. The wars of the Lord (Num. 21:1414Wherefore it is said in the book of the wars of the Lord, What he did in the Red sea, and in the brooks of Arnon, (Numbers 21:14)). The quotation is poetry, so that the book may have been a collection of odes by Moses on the wars of Jehovah.
7. Book of Jehu (2 Chron. 20:3434Now the rest of the acts of Jehoshaphat, first and last, behold, they are written in the book of Jehu the son of Hanani, who is mentioned in the book of the kings of Israel. (2 Chronicles 20:34)). These various references show that when the historical parts of the Old Testament were written, further information respecting the kingdom was obtainable from the books referred to, if such had been needed; but which was not required for the inspired volume of God.

From Manners and Customs of the Bible:

Job 19: 23-24. O that my words were now written Oh that they were printed in a book! that they were graven with an iron pen and lead in the rock forever!I See also Jeremiah 17: 1.
Three different substances for the preservation of record’s are usually supposed to be referred to here: 1. Books. These were anciently made of linen or cotton cloth, skins, or the leaves of the papyrus. From the last word comes our English word, paper. The inner bark of trees was also sometimes used. The Latin word for bark being liber, this word at length came to signify a book; it is still found in the English word library. When made of cloth or skins the book was made up in the form of a roll. See note on Isaiah 34:44And all the host of heaven shall be dissolved, and the heavens shall be rolled together as a scroll: and all their host shall fall down, as the leaf falleth off from the vine, and as a falling fig from the fig tree. (Isaiah 34:4) (#511).
2. Leaden tablets. These are of high antiquity. In 1699 Montfaucon bought at Rome a very old book entirely made of lead. It was about four inches long and three wide, and had a cover and six leaves or sheets. The hinges and nails were also made of lead. The volume contained Egyptian gnostic figures and inscriptions in Greek and Etruscan characters.
In a temple in the Carian city of Cnidus, erected in honor of Hades and Persephone, about the fourth century before Christ, the women were in the habit of depositing thin sheets of lead on which were written the names of persons they hated, together With their misdeeds. They also inscribed on the lead tablets imprecations against those who had thus injured them. Many of these tablets were discovered in 1858 when excavations were made in the ruins of the temple. They are now in the British Museum.
It is not, however, certain that Job in the text refers to leaden tablets or leaves on which inscriptions were made. He may have alluded to the custom of first cutting letters in stone and then filling them up with molten lead. There are indications that some of the incised letters in Assyrian monuments were filled with metal. M. Botta states that the letters on the pavement slabs of Khorsabad give evidence of having been filled with copper. See Layard's Nineveh and Its Remains, vol. 2, p. 188.
The some records of ancient Oriental nations, which modern discoveries have brought to light, are all illustrations of the custom which Job evidently had in mind. Many of these bear on Scripture facts and history, confirming and supplementing the sacred record. The most remarkable, in some respects, of any of these ancient monuments is the famous Moabite stone, the discovery of which in the year 1868 created such intense excitement among biblical scholars and antiquarians. This is the very oldest Semitic inscription of importance as yet discovered, and is the only one thus far found which reaches back to the age of the Jewish monarchy. It gives the Moabitish account of the conflict described in the 2 Kings 3.