average # of weighted citations received in a year
# of documents published in previous 3 years
CiteScore is the number of citations received by a journal in one year to documents published in the three previous years, divided by the number of documents indexed in Scopus published in those same three years.
CiteScore for 2015 counts the citations received in 2015 to documents published in 2012, 2013 or 2014, and divides this by the number of documents published in 2012, 2013 and 2014.
SNIP (Source Normalized Impact per Paper) Calculation