What is a DOI?
DOI is Digital Object Identifier. The DOI name is a unique alphanumeric code that may be assigned to any digital content. The DOI name enables researchers to identify and locate a digital document, even if its original web host has changed. There is a good explanation in the Mahoney Library Guide to APA Style, updated 07/2008 available at http://www.cse.edu/dotAsset/121546.pdf