Łukasiewicz, (1951) Aristotle's Syllogistic from the Standpoint of Modern Formal Logic, Chapter IV "Aristotle's System in Symbolic Form" (section on "Explanation of the Symbolism"), pp. 78 and on.
Łukasiewicz, (1951) Aristotle's Syllogistic from the Standpoint of Modern Formal Logic, Chapter IV «Aristotle's System in Symbolic Form» (секція «Explanation of the Symbolism»), сторінка 78 і далі.