>>>However, I need a good link explaining each method in details. So far in a quick google search I didn't find such a page.
>>
>>Because UT is ungooglable. These methods were discussed at length here.
>
>Are you sure? I still will prefer an external link with good information rather than a discussion thread.

I never got a hit from Google to UT. I also don't know of any external links - all my knowledge comes from hours spent with about dozen accountants over the years. Where they got it, I don't know - probably somewhere during their education. Maybe you should look in the direction of economy and cost calculation, not coding.

But I do remember we had good discussions here, and whatever I contributed then is probably better than what I know now, simply because it was fresher :).