The importance of a source’s date of publication varies according to your writing situation. For example, if you’re writing a feature article on the use of superconducting materials in new mass-transportation projects, you probably won’t want to spend a lot of time with articles published in 1968. However, if you’re writing about the 1968 presidential contest between Hubert Humphrey and Richard Nixon, then sources published during that time period will take on greater importance.

Print sources usually list a publication date. However, it can be difficult to tell when Web sources were created. When in doubt, back up undated information found on the Web with a dated source.