Using dcu style with natbib, some references show as question marks while others do not. I have included examples of references that do work alongside those that do not work as well as the code I am using. Why do the references that are listed as not working show as question marks [?] in the generated report despite using the exact same code? This is the preamble:

\usepackage{natbib, har2nat}

Some Text with citations
These work with \citep and with \cite
\citep{bertrand_are_2004, bertrand_implicit_2005} \citep{bertrand_field_2016}

these do not work regardless



Examples of references created with Zotero integration that generate correctly:

    title = {Luck or {Skill}? {A}-{Team} {Players} {Don}'t {Get} {Sued}},
    volume = {31},
    copyright = {Copyright American College of Physician Executives Sep/Oct 2005},
    issn = {08982759},
    shorttitle = {Luck or {Skill}?},
    url = {http://undefined/docview/199986499/abstract/5689B23D75474D34PQ/1},
    abstract = {Every year, roughly one out of seven doctors gets sued, and if one is in a high-risk specialty, the odds are particularly grim. Yet some physicians practice year in and year out without ever being slapped with a lawsuit. Accomplished lawsuit-free doctors from across the country were interviewed and it was found that physicians are not necessarily at fate's whim. Using lessons from their own patients, they made their own luck. Strait Fairey, MD, has been a family physician for more than 30 years and says he has not been sued because the Lord looks out for some of them sometimes, and because his communication skills have kept him out of trouble. Donald Pocock, MD, FACP, CPE, has been in practice for 32 years, mostly with a busy internist group in Eastern North Carolina. He has never been sued, but there is not a doctor alive who has not made a mistake or had a bad outcome.},
    language = {English},
    number = {5},
    urldate = {2019-05-09TZ},
    journal = {Physician Executive; Tampa},
    author = {Bartelme, Tony},
    month = oct,
    year = {2005},
    keywords = {Fate, Health Facilities And Administration, Litigation, Medical malpractice, Physicians, Skills},
    pages = {22--6}

    title = {Are {Emily} and {Greg} {More} {Employable} than {Lakisha} and {Jamal}? {A} {Field} {Experiment} on {Labor} {Market} {Discrimination}},
    volume = {94},
    url = {http://www.jstor.org/stable/3592802},
    language = {en},
    number = {4,},
    journal = {The American Economic Review},
    author = {Bertrand, Marianne and Mullainathan, Sendhil},
    year = {2004},
    pages = {991--1013}

    title = {Implicit {Discrimination}},
    volume = {95},
    issn = {0002-8282},
    url = {https://www.aeaweb.org/articles?id=10.1257/000282805774670365},
    doi = {10.1257/000282805774670365},
    language = {en},
    number = {2},
    urldate = {2019-04-20TZ},
    journal = {American Economic Review},
    author = {Bertrand, Marianne and Chugh, Dolly and Mullainathan, Sendhil},
    month = may,
    year = {2005},
    pages = {94--98}

    address = {Cambridge, MA},
    title = {Field {Experiments} on {Discrimination}},
    url = {http://www.nber.org/papers/w22014.pdf},
    abstract = {This article reviews the existing field experimentation literature on the prevalence of discrimination, the consequences of such discrimination, and possible approaches to undermine it. We highlight key gaps in the literature and ripe opportunities for future field work. Section 1 reviews the various experimental methods that have been employed to measure the prevalence of discrimination, most notably audit and correspondence studies; it also describes several other measurement tools commonly used in lab-based work that deserve greater consideration in field research. Section 2 provides an overview of the literature on the costs of being stereotyped or discriminated against, with a focus on self-expectancy effects and self-fulfilling prophecies; section 2 also discusses the thin field-based literature on the consequences of limited diversity in organizations and groups. The final section of the paper, Section 3, reviews the evidence for policies and interventions aimed at weakening discrimination, covering role model and intergroup contact effects, as well as socio-cognitive and technological de-biasing strategies.},
    language = {en},
    number = {w22014},
    urldate = {2019-04-22TZ},
    institution = {National Bureau of Economic Research},
    author = {Bertrand, Marianne and Duflo, Esther},
    month = feb,
    year = {2016},
    doi = {10.3386/w22014},
    pages = {w22014}

    title = {The {Dynamics} of {Discrimination}: {Theory} and {Evidence}},
    url = {https://economics.sas.upenn.edu/system/files/working-papers/18-016%20PIER%20Paper%20Submission.pdf},
    abstract = {We model the dynamics of discrimination and show how its evolution can identify the underlying source. We test these theoretical predictions in a field experiment on a large online platform where users post content that is evaluated by other users on the platform. We assign posts to accounts that exogenously vary by gender and evaluation histories. With no prior evaluations, women face significant discrimination. However, following a sequence of positive evaluations, the direction of discrimination reverses: women’s posts are favored over men’s. Interpreting these results through the lens of our model, this dynamic reversal implies discrimination driven by biased beliefs.},
    language = {en},
    journal = {Penn Institute for Economic Research},
    author = {Bohren, J Aislinn and Imas, Alex and Rosenberg, Michael},
    month = jul,
    year = {2018},
    pages = {76}

These references were exported at the same time but do not work:

    title = {What {Doctors} {Feel}: {How} {Emotions} {Affect} the {Practice} of {Medicine}},
    volume = {28},
    issn = {1042-5055},
    shorttitle = {What {Doctors} {Feel}},
    url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4211592/},
    doi = {10.7899/JCE-14-23},
    number = {2},
    urldate = {2019-05-09TZ},
    journal = {The Journal of Chiropractic Education},
    author = {Nyquist, Julie G.},
    month = oct,
    year = {2014},
    pmid = {25222631},
    pmcid = {PMC4211592},
    pages = {173--174}

    title = {Best {Care} at {Lower} {Cost}: {The} {Path} to {Continuously} {Learning} {Health} {Care} in {America}},
    isbn = {978-0-309-26073-2},
    shorttitle = {Best {Care} at {Lower} {Cost}},
    url = {https://www.nap.edu/catalog/13444/best-care-at-lower-cost-the-path-to-continuously-learning},
    abstract = {Download a PDF of "Best Care at Lower Cost" by the Institute of Medicine for free.},
    language = {en},
    urldate = {2019-04-28TZ},
    author = {IOM},
    month = sep,
    year = {2012},
    doi = {10.17226/13444}

    title = {Neuroimaging overuse is more common in {Medicare} compared with the {VA}},
    url = {https://n.neurology.org/content/87/8/792},
    author = {Burke, James},
    month = aug,
    year = {2016}
  • 1
    Check in the blg-file if bibtex reports some errors. – Ulrike Fischer May 10 at 13:44
  • Zotero only exports a .bib file, references.bib, but not a .blg file. I've been searching for this since you posted. Do you know how to find the .blg file? – John May 10 at 14:05
  • 1
    When you run bibtex it creates a blg in the same folder as the bbl. Look for it (if you are using windows: be aware that windows hides extensions or tells you that the file is for some other application). – Ulrike Fischer May 10 at 14:14
  • This worked! Thank you :) If anyone else has this problem. I am using Overleaf. Near where it says "Recompile" there is a list of error messages. Resolving those fixes the problem. – John May 10 at 15:34

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