Below are some starting points so you can research any govco wo/man/business, who would be the respondent in your Notices.
First, see if they are already listed on the Respondents page.
ABN lookup, search for the business name.
Dun & Bradstreet, search the business name, check business structure.
Wikipedia, verify any details, can often provide physical address and full names of respondents (if they are mentioned or have their own Wiki page).
Their website. What ever the business is, they’ll have a website. Use their search options to find the “Executive team” or do a search for “Business X, Chief Executive Officer”, that will often give you the result you need.
eg Search “Parliament of Western Australia” to find the website then search that website for the department eg Legislative Assembly.
You can also go straight to ABN lookup to look for the Legislative Assembly in your state ie
ABN search results Legislative assembly. (most states listed)
Another arm of your state government is the Department of Premier and Cabinet.
ABN search results for Department of Premier and Cabinet. (most states listed)
Wayback Machine
If you find “new” details, or details have been removed, you can always use the Wayback Machine to see if there’s an archive of that page/file/URL.
If you know the URL of a page or a file, put that in the search bar and find archived copies of that page or file (if archives of that page exist). Not every page is archived, and when they are, the archives may be months or years apart. https://web.archive.org/
Law Dictionaries a list of some of the widely used law dictionaries.
It takes a lot of time to research thoroughly, but a well researched document is a well written document. Get your respondents details correct and you hit that nail squarely.