"Synthesis reviews" is an umbrella term for a range of specific review types. The Canadian Institutes of Health Research define synthesis as "the contextualization and integration of research findings of individual research studies within the larger body of knowledge on the topic." They go on to state that "[a] synthesis must be reproducible and transparent in its methods, using quantitative and/or qualitative methods. [...] Realist syntheses, narrative syntheses, meta-analyses, meta-syntheses and practice guidelines are all forms of synthesis."
This page contains a few targeted resources for conducting synthesis reviews in the agricultural or veterinary academic setting.
A chart that includes various places to find grey literature: research, reports, and other materials that are not disseminated by traditional academic publishing.