Anagnostopoulos, I.; Lampropoulou, P.; Tzevelekou, T.; Stivanakis, V.; Kastanaki, A.; Papamantellos, D. Utilization Trials of Lignite Solid Byproducts of West Macedonia and Peloponnesus Lignite Fired Power Plants for the Production of Lightweight Aggregates. geosociety 2013, 47, 1600-1608.