Software watermarking involves embedding a unique identifier into software in order to prove ownership, in a similar way to that of multimedia watermarking. The graph below shows the evolution of software watermarking from the first patents to the latest academic research in the area. The nodes are titles of patents, research papers, or books. Edges of the graph indicate that the items are in some way related, for example one item might build on a previous item, use similar ideas, or discuss a previous idea.
Click the thumbnail image to see the full size timeline.
As far as I know, the graph is accurate and includes all the relevant literature on software watermarking up to 2010.