TWo names I can think of for you to look at.
Alison Kinnard - One of her books is the Harp Key
Heyman, Ann (American, b. Minneapolis, 1951) She became interested in Irish and Scottich traditional music and culture through a wire strung Gaelic harp she discovered. After years of study, she has become a master harpist and teacher. Her book, "Secrets of the Gaelic Harp" is the Bible of Gaelic harpists. She holds master classes all around the world and has served on the faculties of the Edinburgh Harp Festival, the World Harp Festival and the Oberlin College Scottish Harp School, among others, in the techniques of the wire-strung Gaelic harp she has re-discovered. Queen of Harps, #113, #233, Temple Records CD 2057 Ex Te Lux Oritur, #207, Temple Records CD 2057 Sir Thomas Brook's Pavane, #233, #372, above Lord Sheffield's Pavane, #233, #372, above The First Irish Jig, #261, above Holyrood Measure, #261, above Hawk of Ballyshannon, #261, above Temple Hill Reel, #261, above Lament for the Harp, #332, above