Digital Collections of historic maps.
Many libraries and other institutions have collections of digitised historic maps. Here are some places to start:
Identifying and locating historic maps.
Print bibliographies remain useful for identifying maps in both digital collections and paper sources. For a guide to published map bibliographies, see A guide to finding New Zealand historical maps. Also of interest is From sextants to satellites: A cartographic time line for New Zealand.
The Macmillan Brown Library has these bibliographies of New Zealand maps:
Christchurch and Canterbury maps
To find historic Christchurch and Canterbury maps, see the Ĺtautahi-Christchurch subject guide.
Aerial photographs