I want the URL for the Canada Customs and Revenue Agency publication
that lists all the banned books in Canada. I want to download the
aforementioned publication, or buy the said publication.

yoelnatan-ga:

The agency you are interested in is now known as the Canada Border
Service Agency, and here is their website:

http://www.cbsa-asfc.gc.ca/

However, if you search throughout the site, you will find that the
only online publication showing a list of books with import
prohibitions, is for books where a unique Canadian copyright exists
and has been registered:

D9-1-2 Copyrighted Books
http://www.cbsa-asfc.gc.ca/E/pub/cm/d9-1-2/d9-1-2-e.html

These are not the only books where import prohibitions exist, as there
are also publications that cannot be imported due to their content:

D9-1-1 Canada Customs and Revenue Agency's Policy on the
Classification of Obscene Material
http://www.cbsa-asfc.gc.ca/E/pub/cm/d9-1-1/README.html

D9-1-15 Revenue Canada's Interpretative Policy for the Administration
of Tariff Item 9899.00.00 - Hate Propaganda, Treason and Sedition
http://www.cbsa-asfc.gc.ca/E/pub/cm/d9-1-15/README.html 

For items which may fall into these latter two categories, the CBSA is
supposed to form an opinion based on the actual item(s) when import is
attempted. If a list of previously prohibited publications under these
two categories exists, it would only be available from the Prohibited
Importations Unit, at the address shown here:

http://www.cbsa-asfc.gc.ca/E/pub/cm/d9-1-1/d9-1-1/d9-1-1-01-e.pdf

Good luck with your quest!