(Translated title: Volvo trucks yesterday and today) ↑ "How the Baylin Engine Works." Popular Mechanics, July 1946, pp. 131-132. ↑ "Engine With A Built In Tornado." Popular Mechanic, September 1950, pp. 94-95. ↑ "Revolution of the Free-Piston Engine" Popular Mechanics, September 1950, pp. 114-118. ↑ http://www.benz-tools.de/en ↑ Database entry at patents.com ↑ Patent application number: JP2004293387. ↑ http://www.supercars.net/forum/threads/1883-high-speed-engine-with-hot-tube-ignition.19553/