CiteScore Online measures the citation impact of serial titles such as journals. It calculates the average number of citations received in a calendar year by all items published in that journal in the preceding three years. The calendar year to which a serial title's issues are assigned is determined by their cover dates, and not the dates that the serial issues were made available online. In addition to the CiteScore number and percentile ranking, CiteScore also includes the SJR (Scimago Journal Rank) and SNIP (Source Normalised Impact per Paper) numbers.