Traditionally, scientific citations identified those previous studies that informed the piece of work that cited them. But the advent of citation metrics such as Journal Impact Factor and the h index have made citation practice increasingly strategic and sometimes unethical.

In his Editorial for Angewandte Chemie, Jan Reedijk, Leiden University, the Netherlands, explains how such metrics are defined and used to rank individual researchers and entire institutions. He also examines the pressures that such rankings exert on journal editors, referees, and authors and gives examples of practices that push, or overstep, the boundaries of acceptable ethical behavior.

• Citations and Ethics,
  J. Reedijk,
  Angew. Chem. Int. Ed. 2011.
  DOI: 10.1002/anie.201107554