Altitude is only indirectly responsible for high quality, the direct reason is temperatures. Arabica attains a higher quality when it is grown at cool, stable year-round temperatures, and it can never frost. Where are these conditions found? Generally, at high elevation, near the equator. There are exceptions, for instance Hawaii is further from the equator than many other coffee regions, and there specialty coffee is often produced at significantly lower elevations.
Source: multiple authors within this book
Coffee: A Comprehensive Guide to the Bean, the Beverage, and the Industry Published in 2013 by a Miami University professor who runs a small coffee shop that roasts, in Oxford, OH. This book is a wonderful resource for all things coffee: cultivation, roasting, preparing, the industry and many other aspects, etc. I was fortunate to know Dr. Thurston and can tell you he is extremely knowledgeable about coffee, among other things.
This book would probably interest you.
This one is excellent, though it's 2x+ the price of the World Atlas, not sure if it's 2x as good. http://www.amazon.com/Coffee-Comprehensive-Guide-Beverage-Industry/dp/1442214406/