- Witold A. Pogorzelski:
On the Scope of the Classical Deduction Theorem. J. Symb. Log. 33(1): 77-81 (1968) - Marian Boykan Pour-El:
Effectively Extensible Theories. J. Symb. Log. 33(1): 56-68 (1968) - Dag Prawitz:
Hauptsatz for Higher Order Logic. J. Symb. Log. 33(3): 452-457 (1968) - M. K. Rennie:
S3(S) = S3.5. J. Symb. Log. 33(3): 444-445 (1968) - Nicholas Rescher, James W. Garson:
Topological Logic. J. Symb. Log. 33(4): 537-548 (1968) - Daniel Richardson:
Some Undecidable Problems Involving Elementary Functions of a Real Variable. J. Symb. Log. 33(4): 514-520 (1968) - Wayne Richter:
Constructively Accessible Ordinal Numbers. J. Symb. Log. 33(1): 43-55 (1968) - T. Thacher Robinson:
Independence of Two Nice Sets of Axioms for the Propositional Calculus. J. Symb. Log. 33(2): 265-270 (1968) - James Rosenberg:
Functional Completeness in One Variable. J. Symb. Log. 33(1): 105-106 (1968) - Richard Routley, Hugh Alexander Montgomery:
On Systems Containing Aristotle's Thesis. J. Symb. Log. 33(1): 82-96 (1968) - Richard Routley, Hugh Alexander Montgomery:
The Inadequacy of Kripke's Semantical Analysis of D2 and D3. J. Symb. Log. 33(4): 568 (1968) - Raymond M. Smullyan:
Uniform Gentzen Systems. J. Symb. Log. 33(4): 549-559 (1968) - Raymond M. Smullyan:
Analytic Cut. J. Symb. Log. 33(4): 560-564 (1968) - Ivo Thomas:
Replacement in Some Modal Systems. J. Symb. Log. 33(4): 569-570 (1968) - Richmond H. Thomason:
On the Strong Semantical Completeness of the Intuitionistic Predicate Calculus. J. Symb. Log. 33(1): 1-7 (1968) - J. Jay Zeman:
Some Calculi with Strong Negation Primitive. J. Symb. Log. 33(1): 97-100 (1968) - J. Jay Zeman:
Lemmon-Style Bases for the Systems S1 ring- S4ring . J. Symb. Log. 33(3): 458-461 (1968) - J. Jay Zeman:
The Semisubstitutivity of Strict Implication. J. Symb. Log. 33(3): 462-464 (1968)