I'm reading 2 books on my e-reader about apples.  The first is

Apples of Uncommon Character.  by Rowan Jacobsen.  The author reviews more than 100 varieties of apples, most of them seem to be historic varieties but also some of the newest.  It's a bit difficult to page randomly through the book using an e-reader, but there is the convenience of having it when I need it.  He can really pan an apple he doesn't care for - Newtown Pippin "An unassuming smooth green apple the color of a Florida field tomato with a few white dots.  Medium sized and utterly forgetable".  e-edition is $10 less than the book on paper.  Reviews include info on aliases, origin, appearance, flavor, texture, season, uses, region, and history.

The other is:

Apples of North America: Exceptional varieties for Gardeners, Growers, and Cooks, by Tom Burford.  According to the book reviews, the author reviewed 192 varieties of apples.  I didn't count.  Reviews include info on apple appearance, tree characteristics, disease resistance, ripening season, uses, storage.  Not as poetic as Jacobsen's book, but I enjoyed reading the reviews.  e-edition anbout $8 less than the book on paper.

Not books, but the websites where I read about apples to make choices about what varieties to try -

orangepippin.com  Info includes origin, fruit characteristics, uses, growing info including flowering, whether diploid or triploid, vigour, precosity, disease resistance, parentage, offspring, period of origin, history, and votes / comments by people who have grown them.  Some apples have limited info, others are comprehensive.  No cost to use.

I've used the Fedco site for a lot of reading about varieties, but that site seems to be down right now.

These resources are helpful for me to make informed decision on what varieties have a chance to be disease restant, need special pollination partners, have interesting history or flavor traits.

I would love to know other resources.  One can never have too much information.