Do Wikipedia entries really reflect the best scientific evidence available? Study shows that high impact journals behind paywalls are referenced but less often than open access research. mit 
The effect (odds ratio) of a journal’s impact factor vs. open access policy on referencing in
several Wikipedias. pdf
We find that, controlling for field and impact factor, the odds that an open access journal is referenced on the English Wikipedia are 47% higher compared to closed access journals. Moreover, in most of the world’s Wikipedias, a journal’s high status (impact factor) and accessibility (open access policy) both greatly increase the probability of referencing. Among the implications of this study is that the chief effect of open access policies may be to significantly amplify the diffusion of science, through an intermediary like Wikipedia, to a broad public audience. arxiv
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