Sundberg، F.A.؛ Zhao, Y.L.؛ Yuan, J.L.؛ Lin, J.P. (22 سبتمبر 2011). "Detailed trilobite biostratigraphy across the proposed GSSP for Stage 5 ("Middle Cambrian" boundary) at the Wuliu-Zengjiayan section, Guizhou, China". Bulletin of Geosciences: 423–464. DOI:10.3140/bull.geosci.1211.