Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us...
1995, C. K. Ogden, Psyche: An Annual General and Linguistic Psychology 1920-1952, C. K. Ogden, →ISBN, page 13:
Study courses of Esperanto and Ido have been broadcast.
2004, Steven Roger Fischer, A history of language, Reaktion Books, →ISBN, page 180:
The first practical constructed language was the south-west German Pastor Schleyer's Volapük from 1879; its complicated grammar and irregular vocabulary made learning difficult, however. The most successful has been Esperanto, devised by the Warsaw ophthalmologist Ludwig Zamenhof in 1887, that today can count some one million speakers.