Fortey, R., Landing, E., Skevington, D., 1982. Cambrian-Ordovician Boundary Sections in the Cow Head Group, Western Newfoundland, in: Bassett, M., Dean, W. (Eds.), The Cambrian-Ordovician Boundary: Sections, Fossil Distributions, and CorrelationsNational Museum of Wales. pp. 95-129.

Taylor, M., Landing, E., 1982. Biostratigraphy of the Cambrian-Ordovician Transition in the Bear River Range, Utah and Idaho, Western United States, in: Bassett, M., Dean, W. (Eds.), The CambrianOrdovician Boundary: Sections, Correlations, Fossil Distributions, and CorrelationsNational Museum of Wales. pp. 131-139.