Probably the most comprehensive book source for alpine gardening is the North American Rock Garden Society (NARGS).
Take a look. Also the Scottish Rock Garden Club (SRGC). But their website is currently having problems.

Here is a link that might be useful: NARGS

Also try the Alpine Garden Society.

Here is a link that might be useful: Alpine Garden Society

The classic book is the one by H. Lincoln Foster, see http://www.amazon.com/exec/obidos/search-handle-url/index=books&field-author=Foster%2C%20H.%20Lincoln/104-0397208-7066369

A word to the wise - PA has very different weather from Austria and the alps, mainly because it gets a lot more rain and higher temps in summer. Trying to recreate an alp won't work. However, there are thousands of other small plants suited to a rock garden there. Read up and be creative, but don't try to copy what Europeans can do with their mild weather. RJ