Ludwik Lejzer Zamenhof, An Attempt Towards An International Language… (1889)
“ All that is written in the International tongue can be understood by this Vocabulary. If several words together express one idea they must be written in one, but disjoined from each other by a hyphen; for instance, frat-in-o, being one idea, is composed of three words, which must be separately looked for in the Vocabulary. A a expresses an adjective ”
