Surely something simple like :
Code:
(?mi)^(?P<isbn>[\d\-x]{9,17})
Would work better? It includes some leeway for -'s which are often used to space isbn's.
And for fun, here's an over-complex regex to pull out the potentially useful stuff from that formatting :
Code:
(?P<isbn>[\d\-xX]{9,17})\.(?:(?P<publisher>(?:[\w]+\s[\w]*)+)\.)?(?P<title>.+?)(?P<datefudge>(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\w*\.\d{2,4})?(?:\.[^\.]+[\n\r$])