Analysis of information sources in references of the Wikipedia article "웃음" in Korean language version.
Laughter appears to stand in need of an echo, Listen to it carefully: it is not an articulate, clear, well-defined sound; it is something which would fain be prolonged by reverberating from one to another, something beginning with a crash, to continue in successive rumblings, like thunder in a mountain. Still, this reverberation cannot go on for ever. It can travel within as wide a circle as you please: the circle remains, none the less, a closed one.
