h-index, or the Hirsch index is the scientometric indicator proposed in 2005 by Jorge Hirsch to assess scientific productivity. This index is calculated on the basis of citation distribution according to the formula:

  1. A researcher (a team of researchers) holds a Hirsch index h, if h of his Np articles are cited at least h times each, while the remaining (Np-h) articles are cited no more than h times each.

The impact factor of a journal is the average quotation rate of one article. It is calculated by the formula:

  1. The ratio of the number of citations (over a year’s period) of articles published in the two preceding years to the total number of articles published in these two years.