I have just discovered the introduction of an Engineering Master's thesis defended some months ago in my ancient university has been made mostly by "cut & paste" (and literally translate from English to Spanish) part of a book chapter I wrote some time ago. About 80-90% of 10 pages have been copied verbatim from my work.
It is true the author of this thesis cites my work when he copies text without any reference in the original. But since he fails to include such sentences (or any other copied and translated text) as quotes, it seems as if he originally wrote those sentences. The order of the sentences has been somewhat modified, but there is no paraphrasing.
I understand this constitutes plagiarism and I would like to do something about it. I do not intend to undertake legal action or to report this to the university (I do not think it has any normative on the subject, anyway). So, what could I do? Writing the author and explaining him the seriousness of what he did and why? Warning the advisors (whom I know well) about it? Your suggestions will be much appreciated.