I cannot find any information on the author or their qualifications. It could be a translation issue but this reads like it was written by AI.

There are consistency issues, the syntax is awkward and it's unbelievably confusing to read. 

Onto the content of the book, what is this book? What's it about? Whose it for?

The exercises are badly explained, there are no images, no guidance on springs, this is just rubbish.