In the sciences, a primary scholarly source
Primary scholarly references are the gold standard for your background research as a scientist.
Scientific primary literature is peer reviewed, or refereed, before being published. This enhances the quality and validity of the work. In the peer-review process, 2-3 specialists in the field read and critically evaluate the work before it can be published. Peer review is a quality-control measure to ensure that the primary literature includes only high quality, valid scientific information. Primary authors may revise and resubmit articles to improve them.
To learn more about peer-review, check out this short video: "Peer Review in 5 Minutes".
Are the following primary or secondary, scholarly or popular?
So you've started your search. What do you do if....
...you're getting too many results?
Try these tips to narrow down your search:
Use more specific terms and concepts, like "bacterial growth" instead of "microbes" or "Psuedomonas putida" instead of "bacterium."
...you're not getting enough results?
If your searches come up with no results, or only one or two articles, try these strategies before assuming there isn't any information out there!
Check your spelling. It may sound obvious, but look for typos! Databases are programmed to identify some misspellings, but not all of them.
Try broader search words. For example, instead of searching for "amylase", try searching for "enzyme." You can always narrow it down again!