Dong Quai Usage

Can you please let me know how I could find out the dosage information on dong quai?

According to "Bartram's Encyclopedia of Herbal Medicine" (available from Richters), a typical dosage for the dried root is half a cup of decoction made by gently simmering one heaping teaspoonful of root in a cup of water; this half cup dose is taken three times daily.
Bartram's also gives dosage information for liquid extract, tincture, and powder.