I would start with the Australian Stock Exchange archive. http://www.asx.com.au/research/company-research.htm You will need to know the companies ASX code which you will soon discover by reading the share page of any newspaper or by Googling the company.
I would also recommend trying the State library of the home State of the company, e.g. Elders Ltd is domiciled in Adelaide, so its home State is South Australia.
Universities also have very good resources available for this sort of research.
The UniSuper company is an Australian superannuation fund that provides many services to employees of Australia. UniSuper company provides services to the higher education and research sector.
Australian Council for Educational Research was created in 1930.
Australian Wine Research Institute was created in 1955.
BHP (Broken Hill Proprietary Company) is known as "The Big Australian".
The population of Australian Agricultural Company is 500.
Australian Agricultural Company was created in 1824.
South Australian Company was created in 1835.
Australian Broadcasting Company was created in 1929.
Broken Hill Proprietary company limited is a Melbourne based company involved in mining in Australia. This company is sometimes referred to as The Big Australian.
Australian Gas Light Company was created in 1837.
Australian Institute of Company Directors was created in 1990.
Australian Life Biograph Company was created in 1911.