You will often find that credible internet resources are mentioned in your assigned readings and in the scholarly articles that you've searched for.
Most of the internet sites listed here are noteworthy associations or societies that also publish very reputable academic journals.
If you do use Google for an Internet search; use Google Advanced Search for more control over the results. If you limit by Domain you can see the results from goverment sites (.gov), organizations sites (.org), or education sites (.edu). You can also limit by when the site was last updated.
Evaluate sites the way you would evaluate a book or other resource. Who sponsors/publishes it? When was it last updated? Who wrote it? Who thinks it is a good site? Typing "Link: " then the site address in the Google search bar should result in a list of sites that link to that particular web page. Who points to it will tell you something about the usefulness of the page.