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Landing, E., Bowring, S., Fortey, R., Davidek, K., 1997. U-Pb Zircon Date from Avalonian Cape Breton Island and Geochronologic Calibration of the Early Ordovician. Canadian Journal of Earth Sciences 34, 724-730. doi:10.1139/e17-059

Davidek, K., Landing, E., Bowring, S., Westrop, S., Rushton, A., Fortey, R., Adrian, J., 1998. New Uppermost Cambrian U-Pb Date from Avalonian Wales and Age of the Cambrian-Ordovician Boundary. Geological Magazine 135, 305-309.

Landing, E., Bowring, S., Davidek, K., Rushton, A., Fortey, R., Wimbledon, W., 2000. Cambrian—Ordovician Boundary Age and Duration of the Lowest Ordovician Tremadoc Series Based on U-Pb Zircon Dates from Avalonian Wales. Geological Magazine 137, 486-494.

Adrain, J., Westrop, S., Landing, E., Fortey, R., 2001. Systematics of the Ordovician Trilobites Ischyrotoma and Dimeropygiella, With Species from the Type Ibexian Area, Western USA. Journal of Paleontology 75, 947-971. doi:10.1666/0022-3360(2001)075<0947:SOTOTI>2.0.CO;2

Landing, E., Fortey, R., 2011. Tremadocian (Lower Ordovician) Biotas and Sea-level Changes on the Avalon Microcontinent. Journal of Paleontology 85, 680-696. doi:10.1666/10-076.1