From the early 80’s various works have been published which describe the clinical relevance of the nails. A classical example in this field is the work presented by Beaven & Brooks: Color Atlas of the Nail in Clinical Diagnosis (first print: 1984).
Nowadays, general practiotioners are thought during their education that the human fingernail can reveal quite a lot of information about the physical state of health of the subject.
In case you would like to acquire some quick insights in the use of the nails as a diagnostic instrument, try:
The HandResearch Nail Encyclopedia
PS. This website presents also a review on 10 years hand analysis research: www.handresearch.com
