The 1913 Encyclopedia
The previous Encyclopedia of Esperanto was published several times before the 1933 version. In 1913 Petro Stojan proposed a Universal Monograph Encyclopedia (Esperanto: Universala Slipa Enciklopedio), which would be continuously published with separate monographs for each subject. The first five monographs ("The Encyclopedia and its future", "Kinematic theory on time", the hymn "La Espero", "Transcription of proper names", and "Gathering", a poem by L. Levenzon) were published at that time.
Read more about this topic: Encyclopedia Of Esperanto