Color correction is a recent journey for me - a very new & unfinished journey ("and miles and miles to go" comes to mind). So take anything I say about color "correction" with a grain of salt. You've been warned! ;-) And thus warned ... here the books and a couple of websites from which I've been learning:
Skin by Lee Varis - there was one chapter, especially, that broke down skin tone into a very understandable formula.
Professional Photoshop: The Classic Guide to Color Correction by Dan Margulis - this a very thick (both literally and figuatively) book that I will probably be attempting to understand for the next several years. a very valuable reference to have on hand. not so easy to understand, tho.
Pleasing Skin Tone - this is a very helpful online article from SmugMug's site that incorporates ideas from the above two books.
Help for Red Skin Tones - another helpful article from SmugMug.
Visit my Orange County Baby Photographer Website