A method of preventing reduction of sales amount of records due to a digital music file illegally distributed through a communication network is disclosed. The method comprises a)collecting an illegally produced digital music file, which is derived from a record of a cooperating record corporation by...http://www.google.de/patents/US20030078889?utm_source=gb-gplus-sharePatent US20030078889 - Method of preventing reduction of sales amount of records due to a digital music file illegally distributed through communication network
