First Appearance of the word "filk"

SAPS accidentally helped to popularize a new fannish term when it refused to distribute one publication. Lee Jacobs' manuscript on "The Influence of Science Fiction on Modern American Filk Music" was rejected by Wrai Ballard as unmailable. The publicity from his decision helped to put into general fannish use the typographical error, "filk" for "folk." Fannish poems set to pre-existing tunes were known henceforward as 'filk music'.

I note in passing that Harry's definition of "filk" ignores original songs!