Please choose the correct ending to complete the given sentence: Finance and Business: [header] How to look up patent numbers [title] Go to the us patent full-text and image database (patft). [step] The patft holds full-text patents issued from 1976 to the present. [substeps] Older patents exist in the database as pdf images only.

Ending1: Patents must be stamped or numbered for you to find. The fda records patents issued in 2017 without the date. Ending2: Optionally, you may download pdf versions of patents issued from 1983 to 2010. [title] Navigate to the file you want to patecart by using the search box at the bottom right corner. Ending3: However, you can only search for pre-1976 patents if you have the patent number or know the official classification scheme. [title] Gather the information you have about the patent you want to research. Ending4: If you ask the owner who created the patft, then he or she may provide information for you to access the database. Follow the citation guidelines to conduct the google search for patent numbers.

Answer format: ending1/ending2/ending3/ending4