1. Unertan Syndrome quadrupedality, primitive language, and severe mental retardation: A new theory on the evolution of human mind;U Tan;NeuroQuantology,2005
2. Muybridge E (1887) Animal Locomotion: An Electro-photographic Investigation of Consecutive Phases of Animal Movements, 1872–1885: 112 Plates. Published under the auspices of the University of Pennsylvania.
3. Muybridge E (1957) Animals in Motion. Courier Dover Publications. 440 p.
4. Symmetrical gaits of primates;M Hildebrand;Am J Phys Anthropol,1967
5. Primate locomotion: utilization and control of symmetrical gaits;J Vilensky;Annu Rev Anthropol,1989