Commission Regulation (EC) No 661/2004 of 7 April 2004 initiating an investigation concerning the possible circumvention of anti-dumping measures imposed by Council Regulation (EC) No 769/2002 on imports of coumarin originating in the People's Republic of China by imports of coumarin consigned from India and from Thailand, whether declared as originating in India or Thailand or not, and making such imports subject to registration