Now there are 6 spell tomes as I did the 3 rune tomes, each featuring a picture of their respective rune staff pattern. And I also placed the various books in different places including the Arcaneum, Bards College, some castles, inns, shops and houses. I paid attention to place the right books in the right places, especially regarding the interests of court wizards and jarls. I must say that I had quite some fun with Wylandriah, the wizard of Riften who's quite a specimen in her kind already with her scatterbrain mind and silly experiments. Poor J'zargo was also a target of my amusement. I'm not saying more, you'll find out about all of this...
Some of the books though weren't placed already. They are quite unique books and will be found in one location only, a Dwemer ruin I'm building on this purpose. It's quite some fun as well and I hope I can start placing the furniture tonight. I will post some screenshots soon.