1. On the Article Itself:
* Look at the article's first page or the final page. DOIs are usually prominently displayed, often near the copyright information or bibliographic details. They look like this: 10.xxxx/yyyy.
2. On the Publisher's Website:
* If you know the journal or publisher's name, go to their website. Search for the article using the title, author, or date. The DOI will likely be listed on the article's webpage.
3. Using a Search Engine:
* Search for the article's title and author. Often, the DOI will appear in the search results or on the linked article page. You can refine your search by including "DOI" in your search terms. Example: `"Article Title" "Author's Last Name" DOI`
4. Using a DOI Search Engine:
* Websites like Crossref (www.crossref.org) or the DOI Resolver (doi.org) allow you to search for DOIs using article titles or author names. Enter the information you have; if a match is found, the DOI will be displayed. This is a good option if you can't find it using the other methods.
5. Within Library Databases:
* If you accessed the article through a library database (like JSTOR, ScienceDirect, PubMed, etc.), the DOI is usually displayed in the article's record. Look for a field explicitly labelled "DOI" or "Digital Object Identifier".
If you can't find the DOI:
* It's not always necessary to include a DOI in an APA citation. If you cannot locate the DOI after trying these methods, it's acceptable to omit it. In such cases, provide as much bibliographic information as possible, including the URL if the article is online.
Important Note: If you're citing a book, a DOI is less common. You will usually provide the ISBN instead.