More links and websites
This paper by Paul Moon was published in Deep South in 1997. It gives a background to traditional proverbs.
More suggestions and sources
Grace, Patricia. Earth, sea, sky:images and Māori proverbs from the natural world of Aotearoa New Zealand. Nelson: Craig Potton, 2003.
Kōhere, Rēweti T. He konae aronui: Maori proverbs and sayings. Wellington: A. H. & A. W. Reed, 1951.
Mead, Sidney M. Ngā pēpeha a ngā tīpuna: the sayings of the ancestors. Wellington: Victoria University Press, 2001.