Findings:
- Principia
- On Formally Undecidable Propositions of Principia Mathematica and Related Systems
- Principia Mathematica
- Principia Cybernetica
- The Final Problem of Principia
- Principia Ethica
- Principia Mathematica Philosophiae Naturalis
- Philosophia ancilla theologiae
- Principia Discordia
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