But I found some ways which are effective and can be of great help to you who are writing or looking for reliable materials. Well, there's no secret, this techniques are used my most freelance writers out there.First we know that there are a lot of wiki sites in the web that contain reliable information. But wikis are, mostly, not accepted for citation in scholarly papers. So what's the trick? I go directly to their reference links. If I found journal links or article links that are form trusted source, then I am lucky. Most often, wiki sources are also internet sites but are authorities in the topic. Book references found in their articles are also useful as it would give you a hint where to start. If books they site are in your nearest library then again you are lucky.
Next, since journals are sold or subscribed with a fee, publishers want to let their would be subscribers feel the quality of their publication. Because of that they publish some free articles with full contents. Besides other publishers post old issues for free. However old, back issues maybe 3 years old or more, can still be a good source to be cited. There are a lot of online journals available. It is just your searching skill that limits.
Another thing, one approach I use to track down articles is adding PDF at the end of the phrase I searched. So if I'm looking for articles about "Life in the future" I would use "Life in the future PDF" instead. And what would come out is a list of PDF sites. The good thing articles downloaded as PDF is that they contain the page numbers of the document and even their original pagination in the journal source. This is useful since some research papers require the page numbers in the text citations.
Well, helpful or not I guess these things are worth a try.
Good luck to all the freelance writers.