Further, Farther, Lay, Lie: Correct English in a Changing World

"Style Manual"
University of Minnesota

Correct usage of words, from affect/effect to who/whom and -wise.

A pretty good resource.

Not everybody is on the same page, about what's correct, and what's not. Further and farther, for example, are changing in their accepted meanings right now. I think there's a consensus developing, but not everybody agrees:

"Commonly Confused Words"
Further vs. Farther & Lie vs. Lay
Terry Watt (May 1, 2000)
the Carnegie Mellon community

"Several words in English exist as confused pairs. This situation often arises because one word is generally used transitively while the other is generally intransitive. However, at least one special case of simple dualism also exists: the pair further/farther...."

Me, I think that English is changing - and that style manuals like the University of Minnesota's show the way it is - and will be for at least the next few years.