module EPUB
  module ContentDocument
    class XHTML
      attr_accessor :book

      def read
      end
      alias raw_document read
    end
  end
end

module EPUB
  module ContentDocument
    class XHTML
      attr_accessor :item

      def read
        item.read
      end
      alias raw_document read
    end
  end
end

Add attribute "item" instead of "book" to ContentDocument::XHTML
Add attribute "item" instead of "book" to ContentDocument::XHTML
