<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://schema.org/ContactPoint>
<http://www.boomerangbooks.com.au/Geometry-of-Low-Dimensional-Manifolds-Volume-1-Gauge-Theory-and-Algebraic-Surfaces/S-K-Donaldson/book_9780521399784.htm>