"9810010 Grønvik, Oddrun.. Ordet nisset, etc.", Linguistics and Language Behavior Abstracts, 32 (4): 2058, 1998, it is argued that the current material does not give an accurate picture of their distribution in the 19th century.
Binding (2014). endnote 23 to Chapter 4,. Citing Briggs, Katherine (1976). A Dictionary of Fairies. Binding, Paul (2014). "4. O. T.". Hans Christian Andersen: European Witness. Yale University Press. ISBN0300206151.