Here is a remarkably well-preserved CDV of Arthur Cleveland Coxe, the second Episcopal bishop of New York. He was also known as a poet, and from the titles and descriptions of the works, he sounds like a typical mid-19th century American author, which is to say long-winded and basically unreadable to today’s audiences. This must have been a well-known image of him; if you go to Wikipedia to read his biography, you’ll see a copy of this same portrait.
dcphotoartist 
Sir, I am delighted to know of your studies in the platinum process. Please recommend your book or articles that would most assist a CDV collector collecting 1860 to 1875. My thanks and best wishes. Don Woodworth
I don’t have a single reference book to recommend – if there is one I haven’t found it yet. But there are some good general books to help you get a better understanding of what you’re looking at when you see an antique photo. I’d definitely start with “The Collectors Guide to Early Photographs”, by O. Henry Mace. The book has pricing guidelines for each of the categories of images – I’d generally ignore the numbers mentioned because they’re out of date. A four or five year old auction price doesn’t help determine today’s value.
Another helpful title is “The Care of Photographs” by Siegfried Rempel. Beyond that I’d definitely recommend reading some good photographic history books. Spend some time watching the antique photo categories on Ebay to get a feel for what sells at what price point. Certain subjects are hot and collectible right now – this may change with time and they may go up or down in value. Anything Civil War related is popular – CDVs and/or tintypes of soldiers are in high demand. Their relative value, in ascending order, is
Celebrities, politicians and high-ranking officers are somewhere in there, and of course condition can drive value up or down as much as content can.
Another very popular (and growingly expensive) subject area is Native American images, although more of those are Cabinet cards rather than CDVs. Identified subjects by known photographers bring the most money. Occupational images are yet another collectible category, especially ones that clearly show the tools of the trade of the sitter.
Get to know the names of well-known photographers from the CDV era so you can spot their blind stamps on the back. Names like Gurney & Sons, Mathew Brady, Alexander Gardner, Sarony, Bogardus, Eisenmann, C.D. Fredricks, Nadar, W. & D. Downey, should all be familiar to you as marks of a higher-quality image, worthy of collecting.
I hope this helps you get started. If you have any more specific questions, please ask and I’ll see what I can do to help.