Publishers began to routinely assign DOIs (digital object identifiers) to articles in the early 2000s. Now publishers even assign DOIs to other resource types, such as book chapters. However, in the event that an article citation doesn't have a DOI you can search for it in a few ways.
Please note: Generative AI, e.g. ChatGPT, hallucinates citations. If you are not consulting a research-focused generative AI, the citations are likely not real but are formatted correctly which can be deceiving, especially if it the date is after 2005 and there is no DOI.
Option 1: Type the title of an article into JETfind. Remember, you can switch the "Search other libraries too" toggle if you get zero results. 
Option 2: Use the Journal Finder.
- Search for the Journal by title or ISSN
- Go to the Database that has the year coverage for the article's volume and issue (the next steps will look different depending on the database)
- Find the volume and issue
- Browse for the title and/or page range
Option 3: A good old-fashioned Google search. This can help you find the Journal's website if JET Library does not have access to it through one of our databases or collections. Since most Journals do have their archives listed online, even if the full-text of the article isn't, the title of the article should yield something in a Google or Google Scholar search.