Interspecies and intraspecific variability in the trilobites Duyunaspis and Balangia from the Cambrian Series 2 (Stage 4) of Jianhe, South China

1. Chen, Z.
2. Zhao, Y.
3. Yang, X.
4. Esteve, J.
5. Liu, X.
6. Chen, S.
7. Feng, R.