1Fitting M.C. & Mendelsohn R. , First -Order Modal Logic, Kluwer Academic Publishers, 1998, p. 197.
2Stalnaker R. and Thomason R. , "Abstraction in First -order Modal Logic", Theoria 34, 1968, pp. 203-207.
3Fitting M. C. , "A Modal Logic Analog of Smullyan's Fundamental Theorem", Zeitschrifi far Mathematische Logik und Grundlagen der Mathematik, 19( 1973), pp. 1-16.
4Cialdea Mand Luis Farifias del Cerro,"A Modal Herbrand Property", Zeitschrifi far Mathematische Logik und Grundlagen der Mathematik, 32( 1986), pp. 523 -530.
5M. Cialdea Mayer, "Herbrand style Proof Procedures for Modal Logics", Journal of Applied Non - Classical Logics, 3 (1993), pp. 205-223.
6Kurt Konolige, A Deduction Model of Belief, Morgan Kaufman, Los Altos, CA, 1986.
7Fitting M. C. , "A Modal Herbrand Theorem", Fundamenta Informaticae, 28( 1996), pp. 101-122.
8Willard Van Orman Quine, From a Logical Point of View :9 Logico -philosophical Essays, Cambridge, Mass, Harvard University Press, 1980, p. 143.
9Russell B. , On Denoting Mind, 14 ( 1905 ), pp. 479- 493, Reprinted in Robert C. Marsh, ed. , Logic and Knowledge : Essays 1901- 1950, by Bertrand Russell, Allen & Unwin,London, 1956.
10Fitting M. C. , Bertrand Russell, "Herbrand's Theorem, and the Assignment Statement", Artificial Intelligence and Symbolic Computation, Springer, LNAI 1476, 1998, pp. 14 -28.
