There are several avenues worth exploring to get at research that is not represented in our databases due to privilege in publishing. Open Access Journals can be a really great resource. Open Access (OA) Publishing is free and allows access to anyone. This means research is not hidden behind and expensive pay wall. Keep in mind that not every Open Access Journal is on the up and up. There are scams and shoddy research/reviews that get published in some OA journals. But there are ways for you to evaluate those OA journals
Another avenue is to find scholarly blogs. Oftentimes professors and researchers are talking about their work on blog sites. Just like with any other resource, you will need to evaluate the blog to see if it is credible or not. Here is a website to help you do that