Chairs, Tables, Sofas and Beds by Marvin Schwartz (1983, Paperback)

If someone told me I could only have one book in my library about furniture, this would be the one I would choose. It is an education, easy to use, lots of pictures, realistic values (for the time of publishing, but you can do the appreciation thing...) how to spot fakes, all elements of construction, hardware,etc. It's out of print, now, so the best way to get a reasonably priced copy is to shop on E-Bay.