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Top 15 journals (A), most productive authors (B) and their proportion of first- authorship and senior-authorship to co-authorship. A: Top 15 ranking of journals by the number of published items and their impact factor items during the period 1920–2012 B: 15 most productive authors and their h-index in the period 1920-2012 C: 15 most productive authors considering the proportion of first-authorships and senior-authorships to co-authorships.
