“Von Uexküll was interested in how living beings subjectively perceive their environment. Picture, for example, a meadow as seen through the compound eyes of a fly, and then again as seen in black and white by a dog, and heard in a wider range of sounds. Von Uexküll called these subjective worlds Umwelt.” from Jakob_von_Uexküll

http://www.math.uni-hamburg.de/math/ign/hh/biogr/uexkuell.htm

• Archiv für Umweltforschung und Biosemiotik » http://www.math.uni-hamburg.de/home/rueting/Projekte.htm
• Jakob von Uexküll Centre » http://www.zbi.ee/%7Euexkull/

• Jacob von Uexküll, Umwelt und Innenwelt der Tiere., Springer, Berlin 1909.
• 2nd order » http://www.zbi.ee/~uexkull/pubuex.htm