A recent discussion, on another board, has prompted these links: <A HREF="http://www.neuroacoustic.com/articlecells.htm" target="_blank">http://www.neuroacoustic.com/articlecells.htm</A> <A HREF="http://www.amazon.com/gp/product/0966435435/ref=pd_sim_b_1/104-5860235-1307913?%5Fencoding=UTF8&v=glance&n=283155" target="_blank">http://www.amazon.com/gp/product/0966435435/ref=pd_sim_b_1/104-5860235-1307913?%5Fencoding=UTF8&...</A> <A HREF="http://www.amazon.com/gp/product/0060915870/ref=pd_sim_b_2/104-5860235-1307913?%5Fencoding=UTF8&v=glance&n=283155" target="_blank">http://www.amazon.com/gp/product/0060915870/ref=pd_sim_b_2/104-5860235-1307913?%5Fencoding=UTF8&...</A> <A HREF="http://www.amazon.com/gp/product/0914918966/104-5860235-1307913?v=glance&n=283155" target="_blank">http://www.amazon.com/gp/product/0914918966/104-5860235-1307913?v=glance&n=283155</A>