I just received word from the author that the book is now freely downloadable in English, at this link.
Got it. I remember browsing the pages of this book. But it was in Greek, and it does not appear to have been published also in English:
Euclidean Economics: A Mathematical Method for Construction and Application of Economics Models
"The book establishes that economics can be studied and utilised on
the basis of a minimum of fundamental hypotheses and the general laws
of mathematics. Starting from 12 major propositions, it proves that
closed exchange networks are replicated by systems of 2n first-order
non-homogeneous linear differential equations, which simulate
household, business, bank and government receipts and payments. Such
networks are defined in the (R2n, t) vector space, where n is the
number of sectors or markets and countries or currencies, while t is
the elapsed time. Uniqueness, stability and controllability of the
steady state as well as takings and outgoings are functions of
behaviour coefficients and policy parameters. Annual sales of
services, products and securities divided by average salaries, prices
and values yield the man hours, output items and liquidity units
traded. Demanded quantities do not coincide with available quantities.
Potential inflation or deflation is proportional to the weighted
deficit or surplus of market goods. Digital animation of the
endogenous variables is possible on the basis of historical, projected
or hypothetical data about the exogenous variables."
Author: Sophocles Michaelides
Publisher: Mesogios Publications – Ellinika Grammata
The summary does not state it clearly, but the "12 major propositions" are Euclidean, as I recall.