Since most people are not aware on how to get (free*) access to scientific papers and journals, so here's a short list of resources.
- Search http://scholar.google.com for the paper. Maybe you'll get lucky and find it somewhere for free.
- If you can only find a paid for version of the paper, get the title, DOI (sort of like an ISBN number) and link to the download page of the paper on the paysite.
- If you don't know the DOI, find it by searching your paper's title on http://crossref.org
- Go to the LibGen site (links here: https://sites.google.com/site/themetalibrary/library-genesis ) and search for the paper. Try searching on title, DOI and download link address
- If out of luck, try http://Sci-Hub.cc and again search on title, DOI and link address.
- If still out of luck, go to http://reddit.com/r/scholar and make a request for the paper there. Read the 'sidebar' (right side of the screen) before posting! To make the request, use the [make request] button in the top part of the sidebar. In your request, make sure to include the title, DOI and link to the paid article. Also mention what you already did to find the paper yourself.
Steps 4-6 may be legally grey or black methods depending on your jurisdiction. Use at your own discretion to research evolutionary biology, bloodless medicine and wild Watchtower quotes ;-)
Any suggestions for other sources are very welcome!
*) This is a howto, not a discussion on the ethical side of sidestepping a paywall to make scientific knowledge available to the public at no cost. If you wish to discuss that, start your own topic please.