I was doing an informal research intern in a research institution more than a year ago, and it's probably the only experience related to the scientific research during my undergraduate time. Basically it's on a specific topic on AI, and I read papers and did the experiments under the instructions of graduate students of the institution. We submitted a paper where I was one of the co-author to a journal, but it was not accepted.
The word informal means:
- I didn't sign an agreement with the institution and thus I didn't get the certificate from the instutution
- I was doing the work with graduate students instead of the faculties of the institution. I even didn't see the professor (the supervisor of the graduate students who guided me). And it's almost impossible to get a letter of recommendation from the professor of the institution)
If I don't mention it in the CV, I will be the applicant with bare research experience.
If I mention it, without a letter of recommendation from a professor related, I will probably lose the credibility of the research experience.
PS: I am applying for a Master Program of Computer Science. I have other interns in tech companies but they are not for scientific research.
What should I do?