BIBLIOFIND, a subsidiary of Amazon.com, was partially shut down after discovering that hackers downloaded the names, addresses and credit card numbers of approximately 98_000 customers over a period of several months. The company discovered the problem, which began in October, after the site was defaced last week, said Jim Courtovich, a company representative. Bibliofind, founded in 1996, matches those seeking rare and used books with a network of booksellers. Since the attacks, Bibliofind has removed customer credit-card information, addresses and phone numbers from its website. Courtovich said the company has notified federal authorities, who are investigating the source of the attacks. At this time, he said, “we have no information to suggest that customer credit cards have been misused.”