"Kleine Völker" ("Little People") is a german source and scenario book for the Cthulhu RPG published by Pegasus Spiele.
It contains a short chapter with background informations on Elves and Elbes, Dwarfs and other "little people" from real myth and legend, not how you might now them from fantasy literature.
The main part are two massive scenarios themed around these "little people":
"Siegfriedslust" by Steffen Schütte and Wolfgang Schiemichen has the investigators search for the famous Nibelungenschatz in the 1920s.
"Gestohlene Leben" ("Stolen Lives") by Florian Hardt puts the investigators in a bad weather situation in the Alps, where they have to spent at least one night in a sinister mountain village. King Laurin and his dwarven kind seem to rule this place...