Finding the texts of the 1835 Declaration of Maori Sovereignty and the 1840 Treaty of Waitangi is a pretty simple thing. The letter here is often cited as a major step toward the annexation of New Zealand, but never reproduced.
It's a funny sort of letter, composed by a rather heavy English hand (Probably William Yate, who also wrote this). I've not seen the original, so can't say whether the men whose names appear at the bottom were actually signed individually, or if they drew their moko (facial tattoo) as was more normal in those days.
The "Tribe of Marian" is named for Marion Du Fresne who visited New Zealand in 1772 and was killed there by Maori who took exception to the Frenchmen fishing in a bay protected by a tapu.
There was a suspicion at this time that France was about to claim sovereignty of New Zealand, or at least parts of it. Akaroa on the Banks Peninsula near Christchurch still has a strong French influence, due to a settlement made there in 1840.
I quite like the final paragraph of this letter, where it is politely requested that the British control their subjects. It warns that should the British subjects continue to misbehave, then Maori are not going to answer for their actions. The last thing you wanted to do in those days was make Maori angry!
Source: Asiatic journal and monthly register for British India and its dependencies. New Series. November 1832. p 133-34