Salzburg can be a pretty crowded place, especially in the summer. Many hotels and other companies involved with the tourism industries are competing for attention and try to "inform" you their way. Be careful when it comes to travel literature. There plenty of good guidebooks around, so I won't go into that.

 However, Salzburg offers a lot more than just sightseeing info - especially in terms of reading. Some great authors and poets have lived in Salzburg, such as Thomas Bernhard, Peter Handke or Georg Trakl. Look up their wikipedia articles and see whether you would like to read more of then; if so, check out the bookshop "Hoellriegl" near the Alter Markt Square - it is said to be the oldest bookshop in the German-speaking world. They do have a selection of English books.

 If you want to read more on the city itself online, try to stick with independent website. A group of locals maintains a website with general Salzburg information for tourists.  The official website of the tourism council can be useful and there is high quality reading on Salzburg at wikipedia.