A comprehensive volume on Medicine
A comprehensive volume on engineering processes
A comprehensive volume on modern weaponry
Good ideas but as the other site said you might be killed for being a heretic by the religious leaders of the day if you go overboard.
The best most accurate flintlock rifle made historically. Lead balls and gunpowder can be made, and with the flint and steel you can make fire.
The Army field manual on first aid & general medicine (I presume there is some such animal). Note, you can make your own penicillin by taking an orange or other citrus fruit and letting it spoil. You will get a fine green mold. That is raw penicillin. You can scrape it off an use it. Most bad germs grow in an alkaline environment. The citrus is acid. I have used this on minor cuts, pimples and sores. Works like a charm.
A comprehensive survivalist manual oriented to construction and engineering. My boys used to have things like the Anarchists Cook Book lying around. One son is now in special forces.