It uses scholar as a search engine, but then it replaces the links in the results. e.g. http://link.springer.com/link-to-paper becomes: http://link.

It uses scholar as a search engine, but then it replaces the links in the results. e.g. http://link.springer.com/link-to-paper becomes: http://link.springer.com.sci-hub.io/link-to-paper As far as I can tell, it works for some articles.