1. Zhu, M. & Ahlberg, P. E. Nature 432, 94–97 (2004).
2. Ahlberg, P. E. & Johanson, Z. Nature 395, 792–794 (1998).
3. Jarvik, E. Zool. Bidrag Uppsala 21, 235–675 (1942).
4. Chang, M. M. Bull. Mus. Natl Hist. Nat. 17, 235–268 (1995).
5. Rosen, D. E., Forey, P. L., Gardiner, B. G. & Patterson, C. Bull. Am. Mus. Nat. Hist. 167, 157–276 (1981).