Useful links when researching vintage patents
European Patent Office — https://worldwide.espacenet.com
My goto resource for vintage patents. Great search facilities and worldwide coverage.
Google Patents — https://patents.google.com
Google's search engine for patents. Quite good, but I prefer the EPO's user interface. Quite often Google links to the EPO website for details.
U.S. Patent Office — https://www.uspto.gov
This site also has trademark information, but the user interface is often confusing and it only covers U.S. documents.