"Barnes & Noble" => "http://search.barnesandnoble.com/bookSearch/isbnInquiry.asp?isbn=$1",
"Amazon.com" => "http://www.amazon.com/exec/obidos/ISBN=$1",
"Amazon.co.uk" => "http://www.amazon.co.uk/exec/obidos/ISBN=$1"
"Barnes & Noble" => "http://search.barnesandnoble.com/bookSearch/isbnInquiry.asp?isbn=$1",
"Amazon.com" => "http://www.amazon.com/exec/obidos/ISBN=$1",
"Amazon.co.uk" => "http://www.amazon.co.uk/exec/obidos/ISBN=$1"