Better World Books Reading Challenge 2018 discussion

My book budget is basically zero right now and I'm not organised enough to make good use of libraries so although a lot of the categories I can go with with books I already own, and I can put a few on my birthday wishlist, there are other categories I'm looking to see what's free to download on Kindle etc. This is obviously easier with categories like (15) A book by a deceased author!

I thought I'd share what I've come up with for anyone else in a similar financial boat.

2. A book independently published: the Buddhist publishing house Shambala publications released this one for free -
Beyond Anger: How to Hold On to Your Heart and Your Humanity in the Midst of Injustice

5. A book that rewrites history
A Connecticut Yankee in King Arthur's Court

8. A book set in the current season
I love reading Christmas books at Christmas time! You can get A Christmas Carol for free easily enough, or The Nutcracker and the Mouse King or The Gift of the Magi. And if you don't like classics there are a bunch of self-published books you can get for free on Kindle if you just type in "free Christmas books" to Kindle search (I can't guarantee these will be any good!)

19. A book with a detective protagonist
You can get all of Sherlock Holmes for free.

Any other suggestions?