If you are looking for a comprehensive modern handbook on keeping chickens in a natural as well as productive way, Harvey Ussery's book is excellent, and currently a bargain as it's on sale for those of you in the US: https://www.chelseagreen.com/product/the-small-scale-poultry-flock-revised-edition/
I have an extensive library, and this is one of the books I have found most useful and refer to most often.
I have an extensive library, and this is one of the books I have found most useful and refer to most often.