Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Hydrogen internal combustion engine vehicle:

This text has been unreferenced on Wikipedia for a very long time. If you can't find a source, be bold and remove it!

"

Tuning a hydrogen engine in 1976 to produce the greatest amount of emissions possible resulted in emissions comparable with consumer operated gasoline engines from that period.[citation needed][7] More modern engines however often come equipped with exhaust gas recirculation (EGR). Equation when ignoring EGR: