Interlinguistics of interlinguistics are, however, not so constructive, but rather descriptive, comparative, historic, sociolinguistic, or concerned with translation by humans or machines. As for Esperanto, which is the most widely used constructed interlanguage, there is a relatively abundant literature about the language itself and its philology (see Esperantology). Only a few of the many constructed languages have been applied practically to any noteworthy extent. The most prosperous were Volapük (1879, Johann Martin Schleyer), Esperanto (1887 Ludwik Lejzer Zamenhof), Latino sine flexione (1903, Giuseppe Peano), Ido (1907, Louis Couturat), Occidental-Interlingue (1922, Edgar de Wahl) and Interlingua (1951, IALA and Alexander Gode), with
The Ludwik Zamenhof Centre a permanent exhibition - Bialystok of Young Zamenhof – and various temporary exhibitions, concerts, film projections, and theatre performances. Moreover, the Centre regularly holds panel discussions, lectures, and literary promotions. The Zamenhof Centre organises also numerous educational workshops for children and teenagers and introduces modern social and educational projects, such as Living Library and „Discover Bialystok” – an outdoor game realised in the urban area of the city. The building where the Ludwik Zamenhof Centre is situated was included in the Jewish Heritage Trail, which was opened in June 2008 in Bialystok. The Trail was created by a group of