New uppermost Cambrian U-Pb date from Avalonina Wales and age of the Cambrian-Ordovician boundary
K.L. Davidek,
E. Landing,
S.A. Bowring,
S.R. Westrop,
A.W.A. Rushton,
R.A. Fortey, and
J.M. Adrain
1998
Article
Geological Magazine
135(3):305-309
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