Holons go back a long way in history, first originating in popularity with Arthur Koestler (a colourful figure to say the least). While Koestler was known both as a writer of fiction and non-fiction, there’s an interesting crossover of researchers convened in 1969. I’m not sure the Michael Lissack is still running the ICSE web site, where there’s at least an interesting synopsis of the contents of these proceedings: (I’ll add some links to people to the participants).
This is a seminal collection of presentations that took place at the Alpbach Symposium in the Austrian Tyrol in March 1969. It is edited by the incomparable Arthur Koestler and J.R. Smythies. In addition to the editors, the rest of the panel reads like a who’s who in systems theory: Paul A. Weiss, Ludwig Von Bertalanffy, Holger Hyden, Jean Piaget, Jerome S. Bruner and C.H. Waddington. Plus, mostly humanists and economists like Viktor E Frankl, Seymour Kety and F.A. Hayek. A closing retrospective was given by W.H. Thorpe.
That being said, I don’t necessarily recommend these 1969 proceedings, for those with an interest beyond history of science. The Alpbach Symposium can be seen as a continuation of an exploration.
The exploration of holons first shows up in the 1967 book, The Ghost in the Machine (on Wikipedia, with a 1968 New York Times book review, viewable on the Internet Archive, and on Worldcat point to libraries ).
Afterwards, there’s a 1978 sequel, Janus: A Summing Up, (on Wikipedia, with a 1978 New York Times book review and a 1978 commentary by Stephen Jay Gould in the New York Review of Books, available for borrowing on the Internet Archive, and physically in libraries according to Worldcat ).
Instead of starting in 1967 and working up through history with Koestler, perhaps it’s better to start nearer the present, and move back through history.
I recommend: Allen, Timothy, and Mario Giampietro. 2014. “Holons, Creaons, Genons, Environs, in Hierarchy Theory: Where We Have Gone.” Ecological Modelling , Systems Ecology: A Network Perspective and Retrospective, 293 (December): 31–41. https://doi.org/10.1016/j.ecolmodel.2014.06.017. A search on Google Scholar unfortunately doesn’t turn up any open access versions, although you could use the ResearchGate entry to request a copy from the author.
For those who are curious for a cursory view of the Allen & Giampietro (2014) paper, there’s an animated presentation (in a mix of Spanish and English), by Miguel Augusto Mendoza Fuentes, “Holons, creaons, genons, environs, in hierarchy theory” (2016) on Prezi.