What should I do when a paper is published similar to my PhD thesis without citation? As part of my PhD thesis I extended an existing method to a new problem. I finished my PhD thesis about 5 years ago and graduated afterwards. After graduation I started working in industry. I never published my thesis (or parts thereof) as a paper, since I was mainly focused on working at the beginning and after several years just was not motivated enough, since I was not pursuing an academic career. 

Using a simple google search about the topic you would be able to find my PhD thesis even though the content cannot be accessed online, but surely could be accessed by contacting my previous school or the library.

I recently found a published paper that pretty much does the same things that I did for my thesis. It makes the same modifications to the existing method and comes to the same conclusions. My thesis is however not mentioned or cited in the paper. I am not implying any sort of plagiarism. Once you think about the problem, those modifications are very natural. It's just that I came up with them earlier.

As said above, I was never really interested in publishing my thesis, but now that I saw the paper I was thinking: Hey, I was the first! They should have at least cited my thesis!

I am now wondering, what my options would be and came up with the following two possibilities:


Well, tough luck! I never published my results and so it just seems fair that somebody else did (assuming that they came up with them independently).
Write the editor of the journal and inform them that the main message from the paper was already covered in my thesis and thus is not novel research. 


So I was wondering, whether number 1 above applies or whether I should go with number 2. Or what would be other possibilities?
Well, if you did not publish, and your thesis is not available, you really can't complain that somebody else's similar independently performed work is not novel - they had no reasonable way of knowing about your work.

Really, the only way to approach it is the first way. And learn that undocumented work buried in a drawer somewhere does not exist as far as the rest of humanity is concerned. Going forward, document and publish (as appropriate) your work (document for internal business use, publish for the outside world).