When accessing information from a World Wide Web homepage, check the bottom of the page to see when the page was last updated. A good general rule is that the page should have been updated within the last three months. Also note that the date of the last update to the homepage may not coincide with the currency of the information. For example, a homepage that was last updated a week ago, may contain information that was produced and not updated since 1990. Primary sources are those original sources of information documenting research results or first-person accounts of events.
Primary sources can include books, journal articles, dissetations, or conference proceedings.
Secondary sources tend to analyze or critique primary sources, thereby providing additional information and perspective. Seconday sources can also be found in books, journal articles, dissertations, and conference proceedings. Reference books like encyclopediae are prime examples of secondary sources. For example, books on theory of relativity written by albert Einstein are primary sources. Books and articles writtens about Einstein's theory of relativity are secondary sources.