@book{83807,
	author = {Haeckel, Ernst, and McCabe, Joseph,},
	title = {The Riddle of the Universe at the close of the nineteenth century},
	publisher = {Project Gutenberg,},
	year = {2013},
	address = {Salt Lake City, UT :},
	note = {Release date is 2013-06-17},
	url = {https://www.gutenberg.org/ebooks/42968}
}