http://familydoctor.org/familydoctor/en/diseases-conditions/nail-fungal-infections.printerview.all.html
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American Academy of Family Physicians
Signs of a fungal nail infection include nails that are discolored, brittle,crumbly, rough, distorted in shape, or separated from the nail bed. This article provides some useful questions to ask your doctor if you suspect that you have a fungal infection of your fingernails or toenails.