一冊[issatsu] one copy (e.g. book)
冊子[sasshi] book
冊子[soushi] written work (esp. a bound text, as opposed to a scroll)
冊数[sassuu] number of books
冊立[sakuritsu] imperial investiture

数冊[suusatsu] several volumes (books)
短冊[tanzaku] long, narrow card on which Japanese poems are written (vertically)
分冊[bunsatsu] separate volume
別冊[bessatsu] separate volume