I'm a big fan of secret codes. You'll find secret messages, hints, and personal information hidden all over this site. Let's begin with an easy one. This is a book cipher. Each number set refers to a specific page and then the word on that page. For example 9th page, 11th word. To unlock the code one need only find the correct book.
Because this is the first puzzle I've posted I'll make it easy and tell you the key book is the 1997 Hardcover Collectors Edition of "The Ultimate Hitchhiker's Guide" by Douglas Adams "Complete and Unabridged".
9-11, 13-135, 13-6, 504-51, 525-78
Post the answer in the comments if you think you have it licked.
If you solve the puzzle and follow its instructions there will be a reward in it for you.