The measurement of scholarly output is critically important to the world of academia, especially with regard to hiring, promotion, and tenure. Citation analysis is one tool for measuring and evaluating research impact by showing how a particular article, author, or publication is graded based on the number of times that author, article, or publication has been cited by other works. A citation search is a look forward in time from the publication of one item, to later works that reference that same item. This paper will preview three metric citation sources that will be useful to anyone doing citation analysis. Some of these tools are subscription-based and others are free. Each tool has its strengths and weaknesses and none of them covers the entire universe of scholarly publications.