Book I.D.
 

I have been converting my discs to hard drive and have been successful starting at book I.D. 1,2,3,4 etc., which corresponds to my disc numbers. But several times when I try to use the next book I.D. the program tells me that it has already been used so I have to use the next book I.D. How Can I check my imports to see what has been assigned to what book I. D. so that I can keep the book I. D. the same as my disc numbers?