Nijaz, I re-read your response and I have a few questions, the number 311 from
the link was just an example, I would like to download all of the main links
subdirectories, not just 311. 
Essentially, if the link contains this
<https://www.slader.com/textbook/9781337624183-calculus-9th-edition/> +
backslash something else, then I would like it to be downloaded.

ALso, how do I get ONLY this domain and not random google ad nonsense?