Li, N. C.; Tewari, K. C. & Hara, T. Hydrogen bonding in asphaltenes and coal. Quarterly report, January 1--March 31, 1979, report, April 1, 1979; (https://digital.library.unt.edu/ark:/67531/metadc1097770/m1/1/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .