To suggest additions to the page, see [[Wikipedia talk:Book sources]].
Note that books before about 1970 usually do not have an ISBN (although if published in the UK during the 1960s, they may have an SBN). One place to get the numbers is the [[Library of Congress]] [shttphttp://catalog.loc.gov/ catalog], although this will tend to give an American ISBN over, say, an Indian (see one of the [[National Depository Centre]]s) or Australian (see [[National Library Australia]]) ISBN. For a Canadian number, you can use the Canadian ISBN Service System – [http://www.collectionscanada.gc.ca/isn/041011-1000-e.html CISS]. If you are adding an ISBN, remember to add only the ISBN for the edition actually cited in the article; a different edition may have different pagination which does not correspond with the citations in the article, and in some cases may even have significantly different content.
Also, note that a registered ISBN, even one which appears with a corresponding book page on a major book distributor database such as [[≥−→→§→·←âAmazonAmazon.com]], is '''''not''''' definite proof that such a book exists. The ISBN is assigned before the book is actually produced, so the publisher can advertise it — but not all such plans come to fruition, any more than in other enterprises. In addition, ISBN and Amazon.com registration seems to have been abused in attempted hoaxes on Wikipedia in the past. National library catalog systems are worth checking: if a book is published in the UK, it has to be sent to the British Library, and if the British Library includes physical dimensions of a book in their catalog system, there's a fair chance it actually exists!
Books are, of course, an excellent source of their own ISBNs; however, a tiny proportion are printed wrongly.
