Key resource for finding patents with full versions of over 130 million patents and patent applications from around 90 countries.
Coverage varies from country to country. Espacenet includes:
German patents from 1877 onwards
French patents from 1900 onwards
British patents from 1859 onwards
US patents from 1836 onwards
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Use espacenet instead of Google's patent search. There's more help on finding patents at https://isguides.hw.ac.uk/patents