1. http://www.simulia.com/.
2. Dennert Poraver GmbH. Poraver 2–4 expanded glass. Retrieved October 11, 2020 from https://www.poraver.com/en/poraver/.
3. International Maritime Organization. Retrieved October 15, 2020 from http://www.imo.org/.
4. OSTHOFF OMEGA GROUP. Omega C-XL expanded glass. Retrieved October 11, 2020 from https://www.lehvoss.de/en/products/other-raw-materials-additives-and-functional-fillers/.
5. Saint-Gobain Weber. Leca 2–4 expanded clay. Retrieved October 11, 2020 from https://www.leca.com.