Some years ago Howie Mitchel made a small book on dulcimers in general and included a record of his playing in the various styles. Originally it was available from Folk Legacy, in Sharon Mtn Rd, Sharon, CT 06069, 1 204 364 5661. The last time I ordered it, Caroline said that the record was no longer available but that she has a tape of the record - it is their label, she can do what she wants - so you'd best check with her as to availability of either item.
This book seems to have been the result of making many of his "lab notes" into a readable dissertation and including music demonstrating various points that he made. He covered making and tuning dulcimers, several styles of playing, a good discussion of modal tunings with music illustrating each, and other neat stuff for the beginner. He has also done a similar work on hammered dulcimers which is interesting as well.