Disposal of fluidized bed combustion ash in an underground mine to control acid mine drainage and subsidence: Quarterly report, March 1-May 31, 1995, report, May 1, 1997; (https://digital.library.unt.edu/ark:/67531/metadc679560/m1/1/: accessed October 23, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .