I have a document with some citations that I am showing in the 'current-opinion-in-microbiology format. For some reason, some of the papers in the reference section show up with the word [Internet].

For example, here is a short bibliography, one reference with the problem and one without.

1. Grassly NC, Kang G, Kampmann B: Biological challenges to effective vaccines in the developing world [Internet]. Philos. Trans. R. Soc. B Biol. Sci. 2015, 370.
2. Huda MN, Lewis Z, Kalanetra KM, Rashid M, Ahmad SM, Raqib R, Qadri F, Underwood MA, Mills DA, Stephensen CB: Stool microbiota and vaccine responses of infants. Pediatrics 2014, 134:e362–e372.

I'll post a bib-tex export of both of these references at the bottom of this thread. I can't see any obvious way they differ so that the first should have [Internet] and the second should not. I tried looking at the current-opinion-in-microbiology.csl stylesheet but it is really short. I'm not even sure I understand how these really concise stylesheets that don't seem to define anything work, maybe it links to somewhere else through one of the urls or something. In any case, I can't figure out what is triggering the behavior. Any suggestions?

## The bibtex of the two citations
@article{grassly_biological_2015,
title = {Biological challenges to effective vaccines in the developing world},
volume = {370},
issn = {0962-8436},
url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4527384/},
doi = {10.1098/rstb.2014.0138},
abstract = {The reason for holding a meeting to discuss biological challenges to vaccines is simple: not all vaccines work equally well in all settings. This special issue reviews the performance of vaccines in challenging environments, summarizes current thinking on the reasons why vaccines underperform and considers what approaches are necessary to understand the heterogeneity in responses and to improve vaccine immunogenicity and efficacy.},
number = {1671},
urldate = {2017-05-31},
journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
author = {Grassly, Nicholas C. and Kang, Gagandeep and Kampmann, Beate},
month = jun,
year = {2015},
pmid = {25964451},
pmcid = {PMC4527384},
keywords = {review, NIHGnotobiotic, systems vaccinlogy},
annote = {Review of vaccine response variability. Introductes a bunch of other review articles.
 
Rather than beginning with extended preclinical studies in mice and other animals, it was proposed that variation in the immune response to vaccines or infection in humans measured in clinical trials or observational studies would identify potential biological mechanisms underlying protective immunity."
 
Three papers consider environmental determinants of vaccine response
Mawa: Latent infection
Prendergast: Malnutrition (not really a factor) \{maybe microme link\}
Verhasselt: Breast milk antigens that contain adjuvents.
 },
file = {PubMed Central Full Text PDF:H\:\\zotero\\storage\\FKTEGC2H\\Grassly et al. - 2015 - Biological challenges to effective vaccines in the.pdf:application/pdf}
}

@article{huda_stool_2014,
title = {Stool microbiota and vaccine responses of infants},
volume = {134},
issn = {0031-4005, 1098-4275},
url = {http://pediatrics.aappublications.org/cgi/doi/10.1542/peds.2013-3937},
doi = {10.1542/peds.2013-3937},
language = {en},
number = {2},
urldate = {2017-06-16},
journal = {Pediatrics},
author = {Huda, M. N. and Lewis, Z. and Kalanetra, K. M. and Rashid, M. and Ahmad, S. M. and Raqib, R. and Qadri, F. and Underwood, M. A. and Mills, D. A. and Stephensen, C. B.},
month = aug,
year = {2014},
pages = {e362--e372},
file = {Stool_Microbiota_and_Vaccine_Responses_o20160507-12217-11d2ni5.pdf:H\:\\zotero\\storage\\FJBBIIRW\\Stool_Microbiota_and_Vaccine_Responses_o20160507-12217-11d2ni5.pdf:application/pdf}
}


## The stylesheet for current-opinion-in-microbiology

<?xml version="1.0" encoding="utf-8"?>
<style xmlns="http://purl.org/net/xbiblio/csl" version="1.0" default-locale="en-US">
<!-- Generated with https://github.com/citation-style-language/utilities/tree/master/generate_dependent_styles/data/current-opinion -->
<info>
<title>Current Opinion in Microbiology</title>
<id>http://www.zotero.org/styles/current-opinion-in-microbiology</id>
<link href="http://www.zotero.org/styles/current-opinion-in-microbiology" rel="self"/>
<link href="http://www.zotero.org/styles/current-opinion" rel="independent-parent"/>
<link href="http://www.current-opinion.com/journals/" rel="documentation"/>
<category citation-format="numeric"/>
<category field="biology"/>
<issn>1369-5274</issn>
<eissn>1879-0364</eissn>
<updated>2014-05-10T23:43:48+00:00</updated>
<rights license="http://creativecommons.org/licenses/by-sa/3.0/">This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 License</rights>
</info>
</style>