The Clarsach Collection
This 3 volume series is a graded collection of Scottish tunes arranged in traditional style for levered, gut-strung clarsach by Karen Marshalsay, clarsach tutor for 7 years at the National Centre of Excellence in Traditional Music at Plockton. Volume 1 is aimed at elementary players and is grades 1-3, volume 2 is for intermediate players and is grades 4-6. Volume 3 is for advanced players, covering grades 7-8 to diploma level.
Taylor's Miscellany is a book intended for new players of small gut-strung lap harps, but would also be suitable for beginners on modern clarsach.
Key Techniques for Harp is a set of 100 exercises and studies of techniques which are useful for players of all types of harp, including gut, especially for ornamentation.
See also Fearghal McCartan's Christmas arrangements for lever harp.