1. An article of manufacture storing computer readable instructions thereon to identify copied content, the article of manufacture comprising: instructions to inspect content in a first source of protectable content using a first technique; instructions to inspect the content in the first source of protectable content using a second technique different than the first technique; and instructions to identify the inspected content as a partial copy of a second source of content based on the inspection using the first technique and the inspection using the second technique, wherein the first technique and second technique do not rely on a digital watermark added to the second source specifically for the tracking of the content of the second source.