I get requests from publishers to link to, and/or reproduce, content here all the time.
Copyright law is pretty clear as to what is legal: Anyone can link to any content on the internet, including "deep links." It is considered "Fair Use" to reproduce a paragraph or two — a small proportion of the total article — in another work. Reproducing the entire work without the Author’s permission is not allowed.
Now you know . . .
illustration via Erik J. Heels