Metric Space
- Hilbert Space — from Wolfram MathWorld
- Hilbert space — Britannica
- Complete Metric Space — from Wolfram MathWorld
- Cauchy Sequence — from Wolfram MathWorld
- Banach Space — from Wolfram MathWorld
QK-4d
- Meet The Four-Dimensional Numbers That Led to Modern Algebra | WIRED
- Imaginary Numbers
- Visualizing quaternions (4d numbers) with stereographic projection - YouTube
- Something Deeply Hidden | Sean Carroll | Talks at Google - YouTube
QK-Mathematical Philosophy
- Introduction to Mathematical Philosophy
- How Wittgenstein might ‘solve’ both philosophy and quantum physics | Aeon Essays
- What Einstein meant by ‘God does not play dice’ | Aeon Ideas
- A Private View of Quantum Reality | Quanta Magazine