Figure 1. Share of cited references in papers published in 2003 in life sciences, health sciences, physical sciences and social sciences categorized into different percentile rank classes.

The red lines refer to the cited references in all papers published in 2003; the other lines refer to cited references in papers with different citation impacts. The graphs in the left column are based on cited references from the years 1996 to 2003, and the graphs in the right column are based on cited references from 2002 only.