@article {7343,
	title = {Quaternionic Klein{\textendash}Gordon equation},
	journal = {Eur. Phys. J. Plus},
	volume = {136},
	year = {2021},
	pages = {612},
	url = {https://doi.org/10.1140/epjp/s13360-021-01602-w},
	author = {S. Giardino}
}
