[1] https://ulemco.com/

[2] Liebherr to premiere its hydrogen prototype engines at Bauma 2022. Press release October 10.th, 2022

[3] www.westport-hpdi.com

[4] www.behydro.com

[5] Commercially operated Wärtsilä engine runs on 25 vol% hydrogen blend, a world first. Wärtsilä Corporation, Press release 23 March 2023