What is the Best Way to Pack Paperback Books?

I have 200 + paperback books that I need to ship.  When I took the boxes off the shelf, the books appear to be in a jumbled mess. The books are sliding into each other.

I want them to arrive in good condition and need to figure out what is the best way to pack them in the boxes.  If I had the right size boxes I could probably make the fit.  I have to use the boxes that I have.

Any suggestions?

I have done the old ship-the-books-around-the-planet thing a few times. Somehow I always end up shipping lots of books when I move, even in the digital age, LOL.
Generally I just have them all laid down so they can't slide around but there are books of all sizes.
if your books are all the same size you might be able to get them laid down in batches with a few placed in the middle like so
----|----|----
to stop them sliding around. Alternatively, you could always bundle groups of books together (with tape around a piece of paper so they books aren't damaged, or even in a plastic bag) so the bundles stay put inside the box.

Thanks, Tereza for the suggestions.  I think your diagram might work.  I tried to remember how they looked when they were shipped to me though that image is lost to time...

I thought about stacking them with the binding up and putting cardboard between the layers.

If you not in a hurry you can use Media Mail (Book Rate) by USPS https://faq.usps.com/s/article/What-is-Media-Mail-Book-Rate

It is one of the cheapest ways to send books.