nLab: de Rham cohomology
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Comprehensive reference with definitions and references, frequently linked in Reddit discussions.
More resources on De Rham Cohomology
Wolfram MathWorld
MathWorld is an online mathematics encyclopedia from Wolfram Research offering detailed, browsable articles on topics across the math spectrum, including algebra, geometry, calculus, and number theory. Each entry includes definitions, theorems, formulas, diagrams, worked examples, and links to further reading.
MathOverflow: Learning de Rham cohomology
Thread with expert recommendations, cross-posted to Reddit.
nLab
Collaborative wiki for mathematics, physics and philosophy written from a category-theoretic viewpoint, with cross-linked entries on categories, functors, adjunctions, topos theory, higher category theory and homotopy theory. Readers can look up precise definitions, examples and references for advanced structural mathematics.