1. Abbott, C. G., 1926, Notes on the nesting of the Band-tailed Pigeon, Condor 29: 121–123.
2. Adkisson, C. S., 1996, Red Crossbill (Loxia curvirostra), In: The Birds of North America, No. 256 ( A. Poole and F. Gill, eds.), Academy of Natural Sciences, Philadelphia, and American Ornithologists’ Union, Washington, D.C.
3. Anderson, T. R., 1978, Population studies of European Sparrows in North America, Occ. Pap. Mus. Nat. Hist. Univ. Kansas 70: 1–58.
4. Bailey, A. M., Niedrach, R. J., and Bailey, A. L., 1953, The Red Crossbills of Colorado, Museum Pictorial No. 9, Denver Museum of Natural History.
5. Bailey, F. M., 1928, Birds of New Mexico, New Mexico Department of Game and Fish, Santa Fe, New Mexico.