Wallender, Lee (8 December 2022) [Originally published 5 February 2013]. Bacon, Kelly; Scott, Sarah (eds.). "What is Greenboard Drywall". Homerenovations.about.com. Archived from the original on 14 April 2013. Retrieved 21 May 2023.
"What is Coal Ash?". Energy & Environmental Research Center. Archived from the original on 16 January 2012. Retrieved 6 January 2012.
Wallender, Lee (8 December 2022) [Originally published 5 February 2013]. Bacon, Kelly; Scott, Sarah (eds.). "What is Greenboard Drywall". Homerenovations.about.com. Archived from the original on 14 April 2013. Retrieved 21 May 2023.