Hi Lee, one of the best references I have found is this little gem by Harry Woodman. It was published by MAP in 1975. He wrote a number of articles appearing in the Windsock publications. I found mine in a used book store a few years ago, but you might check on AbeBooks or e-Bay. I may have a pdf copy in a collection of cd's a friend gave me a while back, I'll take a look... Cheers, Rockie