Esperanto [SEP] location of formation
Zamenhof spent translating literature into Esperanto as well as writing original prose and verse, the first book of Esperanto grammar was published in Warsaw on July 26, 1887. The number of speakers grew rapidly over the next few decades, at first primarily in the Russian Empire and Central Europe, then in other parts of Europe, the Americas, China, and Japan. In the early years, speakers of Esperanto kept in contact primarily through correspondence and periodicals, but in 1905 the first World Congress of Esperanto speakers was held in Boulogne
, and Polish "od" ('than') morphed into Esperanto "ol" ('than'). Sonorants and voiceless obstruents, on the other hand, are found in many of the numerals: "cent" ('hundred'), "ok" ('eight'), "sep" ('seven'), "ses" ('six'), "kvin" ('five'), "kvar" ('four'); also "dum" (