Recommendations for book for caring for mature apples trees please?

Hi All, on this lovely sunny, Sunday

The house I bought last year has two mature apples trees (one culinary and one desert, I think!).

I don't know how old they are, but they are shaped well and last year there was a ton of fruit, most of which went to windfall, long story.

So this is my first year of having two wonderful apples trees and I have no idea how to care for them? I have searched and tons of videos and links came up, but I would rather have one source of information and wondered if anyone could recommend a good, clearly written for novices book or someone to follow who does good YouTube videos please?

I have seen some fruits, just a few, but also a few mottled and browning leaves, so if there is something going wrong, I would like to at least know early, incase there is anything I can do, example should I try and irrigate them as we haven't had much rain in nearly a month?

Many thanks in advance and any advice is most welcome