Kleine Büning, H., &; Lettmann, T. (1986). Classes of first order formulas under various satisfiability definitions. In 8th International Conference on Automated Deduction. Berlin, Heidelberg.https://doi.org/10.1007/3-540-16780-3_119 
LibreCat: /record/19819
DOI: 10.1007/3-540-16780-3_119