It's Susanne Kehrer, Alles klar mit Haut uns Haar. i don't know if there is an english version/translation... Maybe you want to check at amazon... But I'll keep you updated on what I read in it.
Ok, so you're from Germany, too, I didn't know that. You definitely get the book at amazon.de! Also read the Hobbythek book on hair, I loved that one, too!