Two Diseases in Esperanto (Esperanto: Du Malsanoj en Esperanto) is a book written by Hendrik Arie de Hoog and edited by Erik Carlén, published in Sweden in 1954. It deals with the so-called kia‑ism and tiom‑kiom‑ism in Esperanto. De Hoog recommended following the examples of the language's creator, L. L. Zamenhof, concerning Esperanto correlatives. Source: Wikipedia (en)