Grigorov, Alexander. “Exergy Efficiency of Bulgarian Lignite Fired Steam Boiler P-62 at Various Load and Fuel Quality”. International Journal of Sciences: Basic and Applied Research (IJSBAR) 30, no. 4 (December 1, 2016): 138–146. Accessed September 17, 2025. https://gssrr.org/JournalOfBasicAndApplied/article/view/6556.