"Peer reviewed" (or "refereed" journals) are those that subject content to a critical review by other experts in the field prior to accepting a manuscript for publication. Thus, limiting your literature search to the peer-reviewed journals ensures a higher level of scholarship and research methodology. Magazines, trade journals, and newspapers tend to be "non-peer-reviewed," meaning perhaps just the editor or someone who is not an expert in the field has reviewed the content before publishing. How do you know if a journal citation is from a peer-reviewed journal?
Google Scholar is a time-saving, scholarly search interface accessible from within the Google interface. With Google Scholar, you can access peer-reviewed journal articles, books and book sections. For literature searching, specialized databases have more functionality and access more comprehensive results, but Google Scholar is a good tool
Orthographic projection, centred on 40 degrees S, 170 degrees W. Shoreline data from GSHHS ("crude" level), a public-domain source.
DATE:This was long thought to be the only portrait of William Shakespeare that had any claim to have been painted from life, SOURCE:National Portrait Gallery. AUTHOR: John Taylor. This image is in the public domain; PD-ART; This image is in the public domain due to its age; PD-OLD-100.