Evaluation, engineering and development of advanced cyclone processes. Quarterly technical progress report No. 13, October 1, 1993-- December 31, 1993, report, December 31, 1993; (https://digital.library.unt.edu/ark:/67531/metadc670119/m1/1/: accessed December 13, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .