Final Report: Acidic Properties of Doped Aerogels, April 19, 1993 - June 30, 1998, report, June 30, 1998; (https://digital.library.unt.edu/ark:/67531/metadc719390/m1/1/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .