I first learned about Ralph Abraham through the "Trialogues", a video series recorded with Rupert Sheldrake and Terence McKenna. He struck me as brilliant.
Quite the legend. He maintained a website and the full text of his 1996 book is there ("Chaos in Discrete Dynamical Systems: A Visual Introduction in 2 Dimensions", by Ralph Abraham, Laura Gardini, and Christian Mira):
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[ 2.6 ms ] story [ 26.0 ms ] threadhttps://youtu.be/JV7vuNo3dCI?feature=shared
https://alembic.site/tags/Ralph-Abraham
http://www.visual-chaos.org/jpx/