@book{61098,
	author = {Todhunter, I.},
	title = {Spherical Trigonometry: For the Use of Colleges and Schools},
	publisher = {Project Gutenberg,},
	year = {2006},
	address = {Salt Lake City, UT :},
	note = {Release date is 2006-11-12},
	url = {https://www.gutenberg.org/ebooks/19770}
}