While perusing the web looking for information I am going to use in my upcoming web show, I found this link. http://users.telenet.be/fietser/fotos/VM4SD-FVDWsm.pdf
It will take you to a pdf file of a paper written by Frederik Van De Walle of Stockholm, Sweden. It is an interesting read covering 104 pages of information. If you get the time, you really should read this, it is quite enlightening.