In addition to Dr. Deming's books you can check out The Deming Institute (www.deminginstitute.org). They have a "learn" section with blog posts, podcasts, and articles about the Deming philosophy and how it's being used today. Plus they have sections on some of Deming's main teachings (e.g. the Red Bead Experiment).

Out of the Crisis is the one I've read and would recommend. Written in the 1980s, but most of it still applies today.

Both Out of the Crisis and The New Economics are very good.