There are many different ways to "weed" out nonacademic sites during Internet searches.
1. You can use a search engine which only access academic material. One popular search site is Google Scholar. This site will perform searches on the needed material focusing upon scholarly literature only.
2. Be as specific as possible when searching and use "academic" in the search bar (along with the words used to search).
3. Search academic journals, through sites such as JSTOR and EBSCO. These are pay sites, unless you are given access through your school. Many colleges and universities have open subscriptions for their students. Check with your school library if you are given access to any research sites.
4. Prior to conducting your research, type into the search bar "academic research sites." Under this search, you will find numerous places which offer strictly academic research results.
Outside of these suggestions, many initial searches will allow insignificant sites and information to come up. As a reference, many teachers and professors desire sites which end in .org, .gov, .edu and the like. Best suggestion to "weed" out sites during research would be to ignore the sites not supported by .org/.edu/.gov. That said, not all .coms are bad. Check the About pages of .com or .net sites to see who writes and supports the site. About should give credentials and affiliations. If these are valid, then the material should be acceptable.
Links to academic sites have been provided below as suggestions.