What most naturally follows?

How to look up patent numbers
Go to the us patent full-text and image database (patft).
The patft holds full-text patents issued from 1976 to the present.
Older patents exist in the database as pdf images only.
However, you can only search for pre-1976 patents if you have the patent number or know the official classification scheme. Gather the information you have about the patent you want to research.