I urge anybody in proximity of a public library to look for that article (and read the whole encyclopedia as well!). It is a great complement to PE's article, and will help in providing you with a good vulgarized background on image tone management.
Hummm, we don't have it here
Let's hope for a donation, we received a Kodak book not too long ago.
(Yes, I tried to add it into my collection but it was too late as it was cataloged)