The Art and Science of Judging
And whilst I do concur that there is a natural talent in an eye for a dog, I also believe with honest work that eye can be cultivated....
I have spent more than forty years watching movement - albeit with at first humans. But the last 20 or so with dogs. And I have an eye for a dog.
I recommend the books that have been detailed out in this article. But very simply just sit and watch all dogs go by. Not needing to know what breed is which - but just to watch the movement with a soft eye.
Ypu start tp train your eye. You will start to notice limps, irregularities with gait, footfall patterns head down head up, rolling roughness and maybe pacing
Passion and desire to learn will fuel your research. It is a start of a wonderfull hobby and one of the foundations for a very good breeder.