If I send you the citation, can you tell me how much an old book is worth?
I'm afraid there is no easy answer to your question because the value of any book depends on many factors. We do not provide financial appraisals of books, but the Antiquarian Booksellers Association can assist in locating a good rare book dealer for you.
You can also do some research yourself, starting by checking the WorldCat database which will indicate how many copies of the book are held in libraries. You can also check web sites such as Alibris.com, bookfinder.com, or www.abebooks.com, to see what the book is selling for. The official guide to prices of books sold at auction, "American Book Prices Current," is available at major libraries.
If you need more information, the following two web sites are excellent.