<p>I was going to suggest the poor man’s patent but it looks like those don’t hold up well.
[Patent</a> Pending Blog - Patents and the History of Technology: The Poor Man’s Patent, or How to Shoot Yourself in the Foot](<a href=“http://patentpending.blogs.com/patent_pending_blog/2004/11/the_poor_mans_p.html]Patent”>http://patentpending.blogs.com/patent_pending_blog/2004/11/the_poor_mans_p.html)</p>
<p>However, the above link says that keeping a “research book” is pretty close.</p>