Article level metrics are an evolving area. Measures include the number of citations in social media sites, as well as open peer or crowd-based recommendations or reviews.
The traditional proxy measure of impact, the citation, is applicable to the individual article as well. The number of times a given article is cited by other articles can be tracked in the traditional literature. Several databases offer the feature to find articles within their database that cite a given article.
NOTE: Each source of metrics may show different numbers due to differences in the sources they use.
Use Cited Reference search (click on More at the top of the screen to see this option) to identify the target article, select it, then click Find Citing Articles.
See Cited by links below each search result
See Times Cited in this Database link on the left in the single citation view
Raw Data associated with an article is sometimes made available to other researchers for re-use. Resulting articles may cited the original article or the dataset itself.
Citations to a given article may also appear in less traditional contexts such as in social media services. These services can be searched individually to gain numbers of references to an article:
There are aggregating services that report citation numbers from non-traditional, and sometimes traditional, sources.