Zhou, Zhonghe; Clarke, Julia A.; Zhang, Fucheng & Wings, O. (2004): Gastroliths in Yanornis: an indication of the earliest radical diet-switching and gizzard plasticity in the lineage leading to living birds?. Naturwissenschaften91:571-574. PDF fulltext [Архівовано 5 липня 2006 у Wayback Machine.]
Zhou, Zhonghe; Clarke, Julia A.; Zhang, Fucheng & Wings, O. (2004): Gastroliths in Yanornis: an indication of the earliest radical diet-switching and gizzard plasticity in the lineage leading to living birds?. Naturwissenschaften91:571-574. PDF fulltext [Архівовано 5 липня 2006 у Wayback Machine.]