Google Patents covers the entire collection of granted patents and published patent applications from the USPTO, EPO, and WIPO. US patent documents date back to 1790, EPO and WIPO to 1978. Tips to refine and locate patents: After executing an initial search, select the "Search Tools" option on the upper menu, which enables further refining possibilities for your search. Users can also use the Google Advanced Patents Search to retrieve a more refined search result.
Covering period years:
US patent documents date back to 1790, EPO and WIPO to 1978