  Even if not so ancient, the history of the heat engine efficiency at maximum
power expression have been yet turbulent. More than a decade after the
publication of the seminal article by Curzon and Ahlborn in 1975, one's
rediscovered two older works by Chambadal and Novikov, both dating from 1957.
Then, some years ago, the name of Yvon arose from a textual reference to this
famous relation in a conference article published in 1955. Thanks to an
historical study of French written books not anymore published for a long time,
and since never translated in other languages, we bring to light in this paper
that this relation was actually firstly proposed by Henri B. Reitlinger in
1929.
