@book{104196,
	author = {Bird, J. Malcolm and Einstein, Albert,},
	title = {Einstein's Theories of Relativity and Gravitation :},
	publisher = {Project Gutenberg,},
	year = {2020},
	address = {Salt Lake City, UT :},
	note = {Release date is 2020-10-04},
	url = {https://www.gutenberg.org/ebooks/63372}
}