EFODON is the abbreviated title of Europäische Gesellschaft für frühgeschichtliche Technologie und Randgebiete der Wissenschaft eV, a German association dedicated to the study of world mysteries. It publishes a bi-monthly magazine Synesis, with much of the content of its earlier issues available online(a).
The content of the magazine is wide-ranging and inevitably deals with Atlantis as well as a number of other subjects included in Atlantipedia. Gernot L. Geise is on the committee of EFODON and contributes regularly to Synesis. You will also recognise that a number of the other contributors also feature in Atlantipedia.
It is clear that Synesis is sometimes used to promote the intellectual hobby-horses of some of the contributors, so keep your critical faculties at the ready.
(a) https://www.efodon.de/html/publik/sy/sy.html (German)