[Rockhounds] Silicified Middle Ordovician trilobites from Virginia (free PDFs)

[Paul]

Whittington, H.B. and Evitt, W.R., 1953. Silicified Middle
Ordovician trilobites (Vol. 59). Geological Society of America.
https://pubs.geoscienceworld.org/books/book/65/Silicified-Middle-Ordovician-Trilobites
(free download until June 30, 2020)

Whittington, H.B., 1959, Silicified Middle Ordovician
trilobites: Remopleurididae, Trinucleidae, Raphiophoridae,
Endymioniidae. Bulletin of the Museum of Comparative
Zoology at Harvard College. vol. 121, pp. 369-496.
https://www.biodiversitylibrary.org/part/32962#/summary
https://www.biodiversitylibrary.org/page/4778534#page/501/mode/1up

Hu, C.H., 1976, April. 657. Ontogenies of three species
of Silicified Middle Ordovician trilobites from Virginia. In
Transactions and proceedings of the Paleontological
  Society of Japan. New series (Vol. 1976, No. 101, pp. 2
47-263). Palaeontological Society of Japan.
https://www.jstage.jst.go.jp/article/prpsj1951/1976/101/1976_101_247/_pdf/-char/ja
https://www.jstage.jst.go.jp/article/prpsj1951/1976/101/1976_101_247/_article/-char/ja/

Hu, C.H., 1974, September. 635. Ontogenies of two
Middle Ordovician trilobites from the Edinburg Formation,
Virginia. In Transactions and proceedings of the
Paleontological Society of Japan. New series (Vol. 1974,
No. 95, pp. 353-363). Palaeontological Society of Japan.
https://www.jstage.jst.go.jp/article/prpsj1951/1974/95/1974_95_353/_article/-char/ja/
https://www.jstage.jst.go.jp/article/prpsj1951/1974/95/1974_95_353/_pdf/-char/ja

Bruton, D.L. and Nakrem, H.A., 2005. Enrollment in a
Middle Ordovician agnostoid trilobite. Acta Palaeontologica
Polonica, 50(3).
http://agro.icm.edu.pl/agro/element/bwmeta1.element.agro-article-e5a5ef53-3af9-4efd-b8b3-ca3006e0e32d/c/app50-441.pdf

Yours,

Paul H.