Valentim, B, A Guedes, D Flores, C.R Ward, and J.C Hower. 2010. “Variations in Fly Ash Composition with Sampling Location: Case Study from a Portuguese Power Plant.” Coal Combustion and Gasification Products 1 (2): 14–24. https://doi.org/10.4177/CCGP-D-09-00017.1.