Butterfield, Nicholas J. 2003. Exceptional Fossil Preservation and the Cambrian Explosion. Integrative and Comparative Biology. 43(1):166-177. [1] - URL retrieved June 22, 2006
Dominguez, Patricio and Jefferies, Richard. 2003. Fossil evidence on the origin of appendicularians. International Urochordate Meeting 2003. Abstract at [2] - URL retrieved June 22, 2006
LUO, Huilin, FU, Xiaoping, HU, Shixue, LI, Yong, CHEN, Liangzhong, YOU, Ting and LIU, Qi. 2005. New Vetulicoliids from the Lower Cambrian Guanshan Fauna, Kunming. Abstract at [3][liên kết hỏng] - URL retrieved June 30, 2008
Shu, D.-G., Conway Morris, S., Han, J., Chen, L., Zhang, X.-L., Zhang, Z.-F., Liu, H.-Q., Li, Y., and Liu, J.-N. 2001. Primitive Deuterostomes from the Chengjiang Lagerstätte (Lower Cambrian, China), Nature, 414:419-424. (November 11, 2001). Abstract at [4]. - URL retrieved June 30, 2008
Shu, Degan. 2003. A paleontological perspective of vertebrate origin. Chinese Science Bulletin, Vol. 48 No. 8 725-735. April, 2003. Abstract at [5]Lưu trữ 2008-12-11 tại Wayback Machine - URL retrieved June 30, 2008