Q. What is a DOI?
A Digital Object Identifier (DOI) is a unique alphanumeric string used to identify publications and provide a persistent link to their location on the internet. All DOI numbers begin wth a 10.
Many documents that originated exclusively in print may not have a DOI. When available, a DOI can be found on a journal or article's bibliographic details page in a database, or on an article's title page near the copyright information.
APA and MLA styles require a DOI at the end of the citation, when available.