Power Of Vitamin D: 2nd edition Zaidi
A Vitamin D Book That Contains The Most Scientific, Useful And Practical Information About Vitamin D - Hormone D
by Sarfraz Zaidi MD 2nd edition paper & Kindle
Amazon
VitaminDWiki liked the first edition. Latest edition seems even better.
He has a great website
See also VitaminDWiki
Power Of Vitamin D - book review of first edition