According to the Navitas College of Public Safety Author-date referencing guide. p.16:
The only time you may be using these sources is when a specific definition or explanation is required. It is expected that you will consult general reference works to inform yourself about a topic, for example getting an explanation about a historical period, theory or issues from Wikipedia. This is considered to be low level research and you should seek more academic sources (reports, articles or books) for information to include in assignments.
An in-text reference will suffice - there is no need for a reference entry.
(The Macquarie dictionary 1997)
(The Cambridge encyclopaedia of the English language 1995)
Personal Communications wouldn't usually be included in essays. However, they may be used for a research project. It is suggested that you discuss the validity of these types of sources with your lecturer before including them in an assignment.
The following details should be provided for personal communications in a reference list:
The following examples were taken from the Style Manual for Authors Editors and Printers, 6th edn, p.213
S Savieri, interview with the author, 24 April 1999
V Ngu, facsilime, 12 January 2001.
The following details should be provided for theses in a reference list:
Wright, J 2000, Managing offenders in the community - effective or efficient? PhD Thesis, University of Melbourne, Melbourne.
Lewis, J 1998, Essential skills for police officers, M Sc, Monash University, Clayton.
General: (Newburn 2007)
With a page reference: (Newburn 2007, p.13)
General: (Lewis 1998)
With a page reference: (Lewis 1998, p.136)