An increasing number of databases will allow you to see how often an article has been cited in that particular database, and/or search for a cited article or monograph within indexed articles references. In most cases only articles from recent years will have indexed reference lists. The following databases may be of assistance to you in calculating the impact of your work.
CrossRef is an independent membership association, founded and directed by publishers. CrossRef’s mandate is to connect users to primary research content, by enabling publishers to work collectively. CrossRef is also the official DOI® link registration agency for scholarly and professional publications.
Many publisher sites will allow you to find how often a work has been cited by articles in other journals the publisher publishes. Here are some examples: