Te Ara Encyclopedia of New Zealand
This has a great section of biographies, and sections on ‘Government and Nation’, ‘Maori New Zealanders’, and ‘New Zealand Peoples’. A good starting point for most subjects.
New Zealand History
This is like an earlier version of Te Ara. It is still updated and is helpful for quickly checking a story or fact.
National Library of New Zealand
The National Library in Wellington is an amazing repository of the country’s history. You can search the collections and many online collections, including images, on their website.
An amazing online resource, Papers Past contains more than three million pages of digitised New Zealand newspapers and periodicals. The collection covers the years 1839 to 1948 and includes 120 publications from all regions of New Zealand.