Entry in a Reference Book – No Author, No Editor
Entry title. (Date). Title of reference work. Retrieved from http://xxxxx
Notes
If no date can be determined, use n.d. for “no date.”
If edition numbers are not used, include a retrieval date since the definition could be updated.
More Examples
Entry title. (Date). Title of reference work. Retrieved from http://xxxxx
Existentialism.(n.d.). Merriam-Webster dictionary. Retrieved June 19, 2012, from http://www.merriam-webster.com/dictionary/existentialism