1. Alemseged, Z., Spoor, F., Kimbel, W. H., Bobe, R., Geraads, D., Reed, D., et al. (2006). A juvenile early hominin skeleton from Dikika, Ethiopia. Nature, 443, 296–301.
2. Alexander, R. M. (1987). Swim bladder. In McGraw-Hill encyclopedia of science and technology (Vol. S, pp. 41–43). New York: McGraw-Hill.
3. Allin, E. F. (1975). Evolution of the mammalian middle ear. Journal of Morphology, 147, 403–438.
4. Altmann, S. A. (1959). Field observations on a howling monkey society. Journal of Mammalogy, 40(3), 317–330.
5. Amadon, D. (1969). Variation in the trachea of the Cracidae (Galliformes) in relation to their classification. Natural History Bulletin of the Siam Society, 23, 239–248.