@book{108391,
	author = {Whitman, Roger B.},
	title = {Tractor Principles :},
	publisher = {Project Gutenberg,},
	year = {2022},
	address = {Salt Lake City, UT :},
	note = {Release date is 2022-03-05},
	url = {https://archive.org/details/tractorprinciple00whitrich}
}