Two Deep Sustainability Classics

http://palaeos.com/cosmic_evolution/complexity.html

I am in the process of reading Social Systems, Niklas Luhmann, (1984) for the first time. The link above is in PDF format.
I also found a PDf format link of this classic book.
General System Theory Foundations, Development, Applications by Ludwig von Bertalanffy (1968) 

A Luhmann quote i learned this week:
"Reality then is an illusion. But the illusion itself is real."