All PPE can be capitalised if there's a benefit to the organisation from having it and the cost of it can be measured or, to quote the standard: "it is probable that future economic benefits associated with the asset will flow to the entity and the cost of the item can be measured reliably".
If that's met, and falls within the organisation's policy threshold for capitalising, then books can be capitalised. You need to consider IAS 36 as well though - impairment of assets. Eligibility for capitalising is one thing, but whether they're worth their stated amount on the balance sheet is another and books, by their nature - depending on what sort of books it is - are prone to obsolescence and/or damage so might not have a shelf life, so to speak, long enough to bother capitalising them.
