BOOKS .
The word book has come to have many meanings , eg. any collection of sheets of paper ,wood or other material sewn together; a division of written work ( book of the bible) ; and statements of financial accounting (book keeping).
The primary meaning today, is however, a written work either in manuscript or in printed form that is of substantial length.
Books apparently did not come into existence until long after writing, the earliest form being inscriptions was widespread. Early papyri represent litreature in ancient Egypt may possibly be considered as books, although it is customary to speak of the "Book of the Dead" as the first egyptian papyrus books.
The vast literature of the Greeks, collected in the greatest library of the ancient world , in Alexandria was genrally written on large sheets of papayrus which were glued together and rolled up.
(refrence:history.com)