Most oriental and Native American pentatonic flutes have 5 holes, but some only have 4 for simplicity. Since 5 notes can be made using only 4 holes, how useful is the extra hole? - Quora
Ava Maria Tabs for a 5 Hole Native American Flute - YouTube
Basic Music Theory for the Native American Flute (NAF)
Basic-Five Method for Tuning Native American Flutes