MICROSCOPY - handy educational site about microscopy (from Nikon - not endorsed by me)
Scribd - download books on various topics - many are free
BOOKS WITH NO FREIGHT CHARGE: http://www.bookdepository.com/ or
ZENNIOPTICAL - where I get my cheap spectacles ONLINE - just make sure you get the right script from your optometrist first, and your interpupillary (it’s easy - just get a friend to measure the distance between your pupils in mm while you look into the distance - if this is too hard, ask your optometrist.) distance.
Thinkpeptides with handy calculators