Information of a general nature such as facts which are common knowledge (e.g. the Prime Minister is the leader of government in Australia) do not need to be referenced.
It is essential to reference all types of sources whether they are in print or electronic format (eg websites, blogs, online videos) since they are all forms of information generated by an individual or an organisation, and need to be acknowledged for ethical and legal reasons.
More information about Australian and International Copyright can be found via the following links: