resources on disease and control

Hey there friends!

I'm looking for resources about chicken diseases and ways to control them naturally (homeopathy, essential oils).

Books ideal (chicken how-to with a good resource chapter on disease would be handy), online sources, youtube ok but I don't have reliable internet and can't watch YouTube. But it's good to make note here for future reference.

so...
We've fallen down the rabbit hole (chicken hole?) And are about to buy a local free range chicken farm with no less than 2,000 birds ranging around us.
Free range great and all (with no intention of changing that) i find that from 5 - ten percent of any flock (there are nine or so at a time, each six months apart) are sick with differing symptoms. Stress is not a thing here for sure, but im wondering if there is a sickness being passed on as we move them thru cabins.

Thanks wise permie friends!

Danielle, Pigs (and soon loads of chickens!) in France.

These are not natural 'how-to' guides, but are very valuable for understanding poultry health:

Merck Vet Manual - Poultry
The Poultry Site - Diseases of Poultry

I have a natural health care publication, but will need to scrounge around for the link.

Another good source is this PDF Penn State Poultry Health Care