Your WW1 & WW2 listing is for 27 books - as pictured. As the asking price is $4.00 with $4.00 postage, you stand to lose a heap on this listing.
If you want to sell half of them, you need to create a listing for half of them.
Likewise, if you wish to sell them individually (which based on the price I suspect you do), you need to create an individual listing for each book.
As a heads up... be aware that if this item sells as it is and you ship less than the 27 pictured books, you'd be liable for paying the return postage, refunding in full and you should also expect to receive a glowing red dot on your feedback page for your efforts.
