In the only published detective story by historian Anna Bauerova, "Death and Seven Silent Witnesses," THEY are mentioned, among others:
A wrinkled dwarf with a pouch in his hand
A water sprite having breakfast with a face as green as grass
A purple lady with a heaving chest
In a more well-known author's work, THEY appear in the second part.
Name this author.
In accordance with tradition (he-he), an answer without explanation is not accepted. And Google is better than the official source.