Manifolds and Cell Complexes Section 57 in Dave Rusin's Mathematical Atlas. http://www.math.niu.edu/~rusin/known-math/index/57-XX.html
The Optiverse and Other Sphere Eversions Article by John M. Sullivan on sphere eversions, with numerous illustrations. http://www.math.uiuc.edu/~jms/Papers/isama/
3-Manifolds Links to low-dimensional topology resources. http://www.math.unl.edu/~mbritten/ldt/3mfld.html
Crystallographic Topology The Topology of Crystallographic Groups and Simple Crystal Structures http://www.ornl.gov/sci/ortep/topology.html
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