Set out references to published and unpublished reports in the same way. 
GRDC (Grains Research and Development Corporation) (1990). Annual report 1989–90, Australian Government Publishing Service, Canberra.
DEWHA (Australian Government Department of the Environment Water, Heritage and the Arts) (2008). Background document for the threat abatement plan for competition and land degradation by rabbits, DEWHA, Canberra.
EA (Environment Australia) (2001). A directory of important wetlands in Australia, 3rd edn, EA, Canberra.
Note: In June 2003, the title used to refer to Australian Government departments changed from Commonwealth Department of XYZ to Australian Government Department of XYZ. Reports published before June 2003 should have Commonwealth Department of XYZ as the author or publisher; those published after June 2003 should have Australian Government Department of XYZ. If it is not clear in which month a document was published in 2003, use Australian Government Department of XYZ.
For 2 corporate authors:
ABS (Australian Bureau of Statistics) & AIHW (Australian Institute of Health and Welfare) (1997). The health and welfare of Australia’s Aboriginal and Torres Strait islander peoples, ABS cat no. 4704.0, AIHW cat no. IHW2, Australian Government Publishing Service, Canberra.
If it is definitely known that the report is unpublished (ie not accessible to the reader), include unpublished or internal report in the description, and the name of the organisation that produced the report or that the report was produced for:
Brownlow PG & Jones TO (1995). A new method for detecting organophosphorus pesticide residues, unpublished paper presented at the Therapeutic Goods Administration workshop, Thredbo, March 1995.
AusAID (2012). Developmental Leadership Program (DLP) policy brief: the role of local leadership processes and coalitions in development, internal document, June.
Widgets Australia (2005). Sales prospects for 2006, unpublished marketing report.
Some publications include a number of references by the same government author. To avoid multiple repetitions of the spelling-out of a long abbreviation, there are 2 options: spell out the abbreviation only for the first reference in the list (this is the preferred style) or use a 2‑em rule:
DSEWPaC (Australian Government Department of Sustainability, Environment, Water, Population and Communities) (2010). Publication number one, DSEWPaC, Canberra.
DSEWPaC (2011). Publication number two, DSEWPaC, Canberra.
DSEWPaC (2012). Publication number three, DSEWPaC, Canberra.
or
DSEWPaC (Australian Government Department of Sustainability, Environment, Water, Population and Communities) (2010). Publication number one, DSEWPaC, Canberra.
—— (2011). Publication number two, DSEWPaC, Canberra.
—— (2012). Publication number three, DSEWPaC, Canberra.
