@book{109241,
	author = {Hubble, Edwin,},
	title = {Extra-galactic nebulae},
	publisher = {Project Gutenberg,},
	year = {2022},
	address = {Salt Lake City, UT :},
	note = {Release date is 2022-06-30},
	url = {https://hdl.handle.net/2027/uc1.b3805680}
}