In Perceiving, Acting, and Knowing, edited by Robert Shaw and John Bransford, ISBN 0-470-99014-7. ↑ James J. Gibson (1979), The Ecological Approach to Visual Perception, ISBN 0-89859-959-8. ↑ Uexküll, Jakob von (1980 [1920 etc.]), Kompositionslehre der Natur, edited by Thure von Uexküll, Frankfurt am Main. ↑ Dorion Sagan (2010). "Introduction: Umwelt after Uexküll". In Jakob von Uexküll; Marina von Uexküll; Joseph D. O'Neil.