The Use of TI-86 Calculator (TI-86 laskimen käyttö) is a side track from my engineering studies (2000-2004). It was born during mathematics courses as I learnt to use the calculator which I bought. First version was a collection of web pages.
The guide is not a complete guide to stuff you can do with this calculator, but reflects the studies on courses.
And before you ask, there is no english version of this guide and there won't be one - unless you translate it. ODF-file can be found from finnish pages for download.
Anyway, there's newer calculator models, so you might be better off just learning them as I did: as you study.