@book{100219,
	author = {Spencer, Herbert, and Widger, David,},
	title = {Index of the Project Gutenberg Works of Herbert Spencer},
	publisher = {Project Gutenberg,},
	year = {2019},
	address = {Salt Lake City, UT :},
	note = {Release date is 2019-04-29},
	url = {https://www.gutenberg.org/ebooks/59393}
}