[gutvol-p] Programmatic fetching books from Gutenberg

I made a ebook reader (here) http://code.google.com/p/bookjar/downloads/list and i'd like to search and download Gutenberg books. I already have a searcher prototype using LuceneSail a library that uses Lucene to index rdf documents and only indexing what i want from the catalog.rdf.zip. Now i'd like to know how from the url inside the catalog i can fetch the book itself, and what are the variants for the formats. A example query result: author: Shakespeare, William, 1564-1616 url: http://www.gutenberg.org/feeds/catalog.rdf#etext1802 title: King Henry VIII So, i like to know how from the etext1802 number can i get a working url to download the book, and how to construct variants for each format. Thank you in advance.