"Cover pages" in Three Kingdoms Period China?

I am reading Yu Sumei's translation of Romance of The Three Kingdoms and a particular detail struct me as weird.

Spoiler alert, I guess. In chapter 47, various schemes relating to the fire attack on Cao Cao's forces in the Battle of Red Cliffs are being discussed and executed and we are introduced to Pang Tong who will eventually come up with the plan to chain Cao Cao's ships together.

And there's this character who sees Pang Tong and immediately knows he is really smart because he sees him reading The Art of War. In this period of time in China, if you saw someone reading, would you have any way of knowing what book it was? Did they have cover art or something? What were books even like in this time and place? Would they have been a compact collection of pages bound in some kind of spine? Or would they have been something else?