Digital Object Identifiers (DOIs) are unique and persistent identifiers of objects, such as research papers. They can be resolved by prefixing them with "http://dx.doi.org/". When resolved, DOIs lead to a web page about the paper, hosted by the publisher of the paper. Institutions who subscribe to receive access to publications from certain publishers often provide a proxy through which their users can freely access publications, e.g. http://dx.doi.org.wwwproxy0.library.unsw.edu.au/ for access from UNSW.