I just finished World War Z, but it took me like 2 years, because I kept putting it down and picking it up months later. And because there are no proper chapter titles or anything, I probably read the book about 3 times, because I kept re-reading chapters each time I returned to it.
Currently I have only 1 fiction book on me, and that is 'The World of Ice and Fire' by George R. R. Martin, Elio M. Garcia and Linda Antonsonn.
But it's slow because I've not dedicated much time to it, and my oh my is it wordy. But it provides a hell of a great backstory to A Song of Ice and Fire.
I think a large amount you hear in tidbits while reading aSoIaF, but this just puts it all there for you in one go. Saves you having to spend ages on the Wiki.
Other than that, only really historical books or a few pieces of Scholarship.
I've not read through the whole thing, because it would be a bit awkward, but I had to read and use bits of Dioscoride's Greek Herbal, which is a Roman book on herbs, animals and minerals, and their use in medicines. Some of the stuff is crazy.
Here's an example;
Book 2, 78
Gala Gunaikos. "Woman's Milk"
"But woman's milk is the sweetest and most nourishing. Being sucked it is good for the gnawing of the stomach & the Consumption. It is good also for one that has drank down a Sea-Hare. Being mixed with Franckincense beaten small, it is dropped into eyes that are bloodshot by a blow. And it is good for the gout, being annointed on with Meconium & Ceratium. But all milk is naught for the spleneticall, the Hepaticall, for the Vertiginous, Epileptical & such as are troubled in their sinews, for such as have fevers, or whose heads do ache, unless at any time one gives them whey for purgation sake, as has been formerly showed.
Some say that the milk of a bitch when she first whelps does do away with hair, being annointed on & that being drank, it is an Antidote against poisonous medicines & that it is a caster out of dead Embryos"
So, basically, Human Milk is the sweetest and most nourishing of milks, and it's good for stomach pains and consumption (I believe this refers to Tuberculosis). It's also good for a bloodshot eye derived from being hit, if you drop it into your eyes.
Also good for gout, if mixed with Meconium (this is the first poo from a baby just born) and Ceratium (unsure of, possibly a plant).
No milk however is good for diseases of the spleen, liver, Vertigo, Epilepsy, painful sinews, fevers or headaches.
Bitch Milk is apparently good for removing hair, if the milk comes from a bitch who has whelped for the first time, and it will also work as an antidote against poisonous medicines, and it will remove dead embryos. (I don't know if this means if you have a miscarriage, or refers to having an abortion. Probably the former)