The Wikipedia has a cool book source lookup tool that I just noticed. If you have a book with the ISBN of “9780304349616” you can create a link like this, The Cassell guide to punctuation which goes to “http://en.wikipedia.org/w/index.php?title=Special:Booksources&isbn=9780304349616”. This opens a page where you can find the book in most accessible card catalogues like Toronto Public Library. The system lets Wikipedia references be followed to local libraries where you could get the book. I should get into the habit of tagging references online this way.