As an extension to the discussion on another thread regarding the merits of providing UVB, it was suggested to start a separate thread on the subject. After a fairly brief search I've found a number of scientific articles which may be of interest to those who are unaware of them. I'll dig them out when I'm not at work and on my phone, but for now here's an interesting read from this very forum:
http://www.frogforum.net/showthread.php?t=24225