I'm presently writing a research paper that needs to include a brief history of the development of arranger keyboards. For current top models, I would like to be able to include reliable estimates of total units sold.

I will, of course, be contacting manufacturers for any help they might provide. Beyond that, though, I'm hoping some of you can send me copies of (or links to) relevant articles in industry-related magazines or other such publications. Any help will be appreciated.

Thanks in advance!

Charles Walker