Alexandre Stefanov long maintained a list of online math texts and other materials at Geocities, but it appears that his original web site is no longer available. Because these resources may be of interest to our readers, we present here a modified version of Stefanov's list as of November 18, 2009. We welcome corrections or suggested additions to this list.

See also Math on the Web, compiled by the American Mathematical Society, for more online math resources.

General Topology

• Topology Course Lecture Notes, by Aisling McCluskey and Brian McMaster
• Topology lecture notes (3rd year), by Thomas Ward
• Foliations and the topology of 3-manifolds, by Danny Calegari

Algebraic Topology

• Allen Hatcher's homepage, has a (nearly complete) textbook.
• Introduction to Sheaf Theory and Algebraic Topology, by Pierre Schapira
• Cohomology, Connections, Curvature and Characteristic Classes, by David Mond
• Introduction to Characteristic Classes and Index Theory, by Jean-Pierre Schneiders
• Abstract group theory and topology articles, by Walter Neumann

K-Theory

• An introduction to algebraic K-theory, by Charles Weibel.

Knots

• Knots Knotes., by J. D. Roberts
• Vassiliev invariants and combinatorial structures, by S. V. Duzhin
• Collection: History of Knot Theory, by Andrew Ranicki
• Lecture Notes On Knot Theory, by Swatee Naik
• Knot theory from Vandermonde to Jones, by Jozef H. Przytycki