Digital object identifier

A digital object identifier (DOI) is a persistent identifier or handle used to uniquely identify various objects, standardized by the International Organization for Standardization (ISO). DOIs are an implementation of the Handle System; they also fit within the URI system (Uniform Resource Identifier). They are widely used to identify academic, professional, and government information, such as journal articles, research reports, data sets, and official publications. DOIs have also been used to identify other types of information resources, like commercial videos.
==Example==
On the page Minor ice hockey the following reference is used:
=== Controversy regarding age distribution in Canadian minor hockey ===
In a 2001 study published by the University of Toronto Press, the effects of minor hockey players who are born in the first half of the year (January–June) were directly compared to those who are born in the second half of the calendar year (July–December). The study aimed to determine how age affects a young player's probability of playing at a higher level in the future. Given the relatively short age brackets in Canadian minor hockey (players move up one league every two years before the age of 15), it was hypothesized that players who are born in the latter part of a calendar year are at a disadvantage (theoretically, a child could be playing with peers who are 2.5 years older than themselves under the current Canadian Minor Hockey system). The findings in this research were consistent with the hypothesis; upon extensive testing throughout several leagues and age divisions in Canada, Hurley, Lior and Tracze concluded that age plays a significant factor in a players ability to excel in hockey beyond the house league level.
Category:Reference organizations