Google Scholar can be useful for finding grey literature, but this 2015 study suggests that it shouldn't be the only source searched:
Haddaway NR, Collins AM, Coughlin D, Kirk S (2015) The Role of Google Scholar in evidence reviews and its applicability to grey literature searching. PLoS ONE 10(9). doi:10.1371/journal.pone.0138237
Note that you'll need to take a different approach to building search strategies in Google and Google Scholar than in many other databases:
For more details, see:
Bramer WM, Giustini D, Kramer BM, Anderson P (2013). The comparative recall of Google Scholar versus PubMed in identical searches for biomedical systematic reviews: a review of searches used in systematic reviews. Systematic Reviews 2(115). http://doi.org/10.1186/2046-4053-2-115
Advanced search operators give you more control over what results Google returns:
Operator | Description | Example |
“Search a phrase” | Forces the specific word order | "This phrase only please" |
"Word" | Quotation marks around a word turns off synonyms & spell checking | "kitten" |
site: | Searches a particular website (ubc.ca) or domain (.ca) | site:gc.ca |
filetype: | Searches for a particular filetype | filetype:pdf |
intitle: | Searches only in the title | intitle:"climate change" |
- [minus sign] |
Removes a word from results. You can use with the word journal and names of major publishers to limit journal results, making it more likely you'll see grey literature |
-journal -ncbi |