aorta is a confusing book but when you learn how to use it it makes sense and is a pretty helpful guide on identifying Roman coins. how the book works is: it lists all the busts, then obverses, then reverses, then types, then mints. Find the correct ruler in the book. Choose the correct information and match it with the pre-matched information after the unchosen information. This is the value of your coin. also provided is information about the ruler and the coins produced by the ruler. below the information on the coins produced by the ruler a rectangle encasing rarity and average price of the coins first, there is the number of coins produced by the ruler and the rarity rating by coinvac (now coryssa http://www.coryssa.org/index.php/home/index) followed by the rank of the coin ex. 85th  concludes with ebay and auction average prices the auction prices refer to the higher-end options, for example, ms64 coins are sold less on ebay than in auctions.