@book{66842,
	author = {Blok, A.},
	title = {Het Esperanto in Twintig Lessen},
	publisher = {Project Gutenberg,},
	year = {2008},
	address = {Salt Lake City, UT :},
	note = {Release date is 2008-06-19},
	url = {https://www.gutenberg.org/ebooks/25841}
}