(Extracted from <https://correlatesofwar.org/data-sets/igos/>)

In any papers or publications that utilize this data set, users are asked to
give the version number and cite the documentation for the data set, as follows
(this citation will be replaced by the article of record for the data set when
information is available):

  Pevehouse, Jon C.W., Timothy Nordstron, Roseanne W McManus, Anne Spencer
  Jamison, “Tracking Organizations in the World: The Correlates of War IGO
  Version 3.0 datasets”, Journal of Peace Research.