Traditional Square of Opposition
PPT - The Traditional Square of Opposition PowerPoint Presentation, free download - ID:6705955
tikz pgf - Square of oppositions diagram - TeX - LaTeX Stack Exchange
Logic & Reasoning – 1000-Word Philosophy: An Introductory Anthology
Ethical Realism
Square of opposition - Wikipedia
Square of Opposition, illustrating logical relations among propositions
PHIL-1003 Textbook Notes - Spring 2017, Chapter 5 - Syllogism, Categorical Proposition, Venn Diagram
PDF) Ploucquet's “Refutation” of the Traditional Square of Opposition