Cite working paper

I am exporting the .bib file from Mendeley and use it in my bibliography. However, working papers only appear with author names and paper title. They miss the working paper series and paper number. The paper number does not even get transferred to the .bib file, although is is entered in Mendeley at the right spot, see attached image.

@unpublished Ifo Institute>, author = , file = , institution = , keywords = , series = , title = >, year = > 

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Using \bibliographystyle or \bibliographystyle followed by \bibliography then gives Brandts, J. and A. Riedl (2017). Market Interaction and Efficient Cooperation. But what I need is: Brandts, J. and A. Riedl (2017). Market Interaction and Efficient Cooperation. CESIfo Working Paper No. 5694. * UPDATE * I updated the entry in Mendeley, see image. In the .bib this gives:

@techreport, author = , file = , institution = Ifo Institute>, keywords = , series = , title = >, year = > 

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In the pdf this still gives: Brandts, J. and Riedl, A. (2017). Market Interaction and Efficient Coop- eration. Technical report, Center for Economic Studies & Ifo Institute, Munich. What I still need is the "technical report" to dissapear, and the paper number needs to be shown.