@misc{indiciae1852faec4c24,
  title = {Distribution and color variation of gyrfalcons in Russia},
  author = {D. H. Ellis and Catherine H. Ellis and G.W. Pendleton and A.V. Panteleyev and I.V. Rebrova and Y.M. Markin},
  year = {1992},
  url = {https://pubs.usgs.gov/publication/5222944},
  note = {Source identifier: 5222944}
}