Cement, Concrete and Research Literature Online Repositories (Portland Cement Association)

Bartlett, G. S., Lesley, R. W., & Lober, J. B. (1924). History of the Portland Cement Industry in the United States With Appendices Covering Progress of the Industry by Years and an Outline of the Organization and Activities of the Portland Cement Association Chicago (IL): International Trade Press, Inc. Google Books. [cited 2021 Aug 31] Available from https://www.google.com/books/edition/History_of_the_Portland_Cement_Industry/QR86AAAAMAAJ.

PCA: since 1916 America's cement manufacturers [Internet]. Skokie (IL): Portland Cement Association; c2019 [cited 2021 Aug 31]. Available from https://www.cement.org/about.