* Unofficial 2011 Impact Factors were established by dividing the number of articles published in 2010 and 2011 were cited in 2011 based on a search of the Google Scholar Citation Index database, by the number of articles published in the previous two years (2010 and 2011).
A = the number of times, articles published in 2010 and 2011, were cited by indexed journals during 2011
B = the total number of "citable items" published by that journal in 2010 and 2011.
(Ref: http://en.wikipedia.org/wiki/Impact_factor)