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- Gregg Miner. Organology: Harp Guitar "Relatives" - Hollow-arm Guitars ("Pseudo" Harp Guitars). www.harpguitars.net. "Note to the casual reader or researcher: This Reference Gallery features historical instruments that are not harp guitars, but “relatives” or distant “cousins” – presented on Harpguitars.net for historical and organological comparison.”, “There are three forms, and they more or less duplicate the three types of Form 3 harp guitars - without the additional sub-bass or harp strings. / Type A / Type B / Type C"