They don't have copyright. And don't think that they need it.

[link|http://www.tnr.com/doc.mhtml?pt=ZXNsxCyVywfPQsxH%2BX3o%2BK%3D%3D|http://www.tnr.com/d...H%2BX3o%2BK%3D%3D]

Cheers,
Ben