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Factual Database
ChemSpider is a free chemical structure database providing fast text and structure search access to over 32 million structures from hundreds of data sources.
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External Library Catalog
The German National Library of Science and Technology (TIB) ‒ Leibniz Information Centre for Science and Technology and University Library is a central specialised library, responsible for operating the German National Library for technology, architecture, chemistry, information technology, mathematics and physics as well as the University Library for Leibniz Universität Hannover. As the world's largest specialised library in its fields, the library has excellent collections of technical and scientific specialist and research information.