These domains will be more likely to contain reliable information:
.gov = government sites which often have statistics and articles produced with funding from your tax dollars. These are not free of bias, depending on those currently managing the site.
.edu = educational institutions. Level of expertise is uneven ranging from the latest paper of a PhD in Organizational Behavior to a book report by a 9th grader.
.org = organizations, sometimes professional organizations. Many have articles and links to work done in their group.
Using the Internet for academic purposes is far different than seeking entertainment or commercial websites. For a site to be acceptable on assignments, be sure it passes the test in each of these areas.
This search restricts results to more academically related sources.
This site searches US government websites such as the EPA, CDC and Census Bureau.