Lie's Structural Approach to PDE Systems
Olle Stormark
I found very difficult to use this book, perhaps it is fault of my mathematical training. Another book "Cartan for Beginners" was slightly more useful. I'm horrified by its price $180.00 (Dec 2008) ! I guess only people with a generous research budget or libraries would buy it. There is a cheaper version printed on Hong-Kong, I bought it but the paper is almost like newspaper. I still wish to find a user friendly book that deals with
_systems_ of PDEs.
