A critical skill for conducting effective research is citation management. We recommend that early researchers begin to keep track of references using one of the many available software packages designed to assist this process as soon as possible. The following Wikipedia page offers a helpful comparison of these products. http://en.wikipedia.org/wiki/Comparison_of_reference_management_software
In addition to the above, a number of websites exist that perform a similar function.
CiteULike http://www.citeulike.org/free online service to organize academic publications See example of our group collection http://www.citeulike.org/group/18310
Endnote Web https://www.myendnoteweb.com/ Web-based reference organizer and writing solution, fully integrated with ISI Web of Knowledge
Connotea http://www.connotea.org/ Free online reference management and sharing for researchers and scientists.