Altangerel, P., Norell, M. A., Chiappe, L. M. & Clark, J. M. 1993:
Flightless bird from the Cretaceous of Mongolia. –Nature: vol. 362, 15
April, pp. 623-626

    Chiappe, L. M. 1992: Enantiornithine(aves) tarsometatarsi and the avian
affinites of the Cretaceous Avisauridae. –Journal of Vertebrate Paleontology:
vol. 12, #3, pp. 344-350

    Chiappe, L. M. 1995: The first 85 million years of avian evolution.
–Nature: vol. 378, 23 November, pp. 349-355

    Chiappe, L. M. & Calvo, J. M. 1994:  Neuquenornis volans , a new late
Cretaceous bird (enantiornithes: Avisauridae] from Patagonia, Argentina.
–Journal of Vertebrate Paleontology: vol. 14, #2, pp. 230-246

    Currie, P. J. & Padian, K. eds. 1997: Encyclopedia of Dinosaurs.
--Academic Press, New York. 1997 xxx-869

    Ericson, P. G. P. 1996: Systematic relationships of the Palaeogene
family Presbyornithidae (Aves: Anseriformes)
–Zoological Journal of the Linnean Society: vol. 121, #4, pp. 429-483

Feduccia, A., 1980: The Age of Birds.

–Harvard University Press, Cambridge, Massachusetts & London, England, 1980, IX-196
Feduccia, A., 1996: The Origin and Evolution of Birds.

–Yale University Press, New Haven, 1996, x-420

    Hou, L.-h, Zhou, Z., Martin, L. D. & Feduccia, A. 1995:
A beaked bird from the Jurassic of China.
–Nature: vol. 377, 19 October, pp. 616-618

    Livezey, B. C. 1996: A phylogenetic clssification of waterfowl
(Aves: Anseriformes), including selected fossil species.
--Annals of Carnegie Museum: vol. 66, #4, pp. 457-496.

    Milner, A. C. 1993: Ground rules for early birds.
–Nature: vol. 362, 15 April, p. 589

Olson, S. L., 1985: The fossil record of birds. 79-239.

in Farner, D., King, J. & Parkes, K. (eds.), 1985: Avian Biology. vol VIII.

–Academic Press, New York. 1985.

    Sereno, P. C. & Chenggang, R. 1992: Early evolution af Avian fligth
and perching: new evidence from the Lower Cretaceous of China.
--Science: vol. 255, 14 February, pp. 845-848

Sibley, C. G. & Monroe, B, L., 1990: Distribution and taxonomy of birds of the world.

–Yale University Press, New Haven & London, 1990. xxiv-1111.