PDF examples
http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1001878
(http://dx.doi.org/10.1371/journal.pmed.1001878)
http://www.plosmedicine.org/article/fetchObject.action?uri=info:doi/10.1371/journal.pmed.1001878&representation=PDF
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0136492
(http://dx.doi.org/10.1371/journal.pone.0136492)
http://www.plosone.org/article/fetchObject.action?uri=info:doi/10.1371/journal.pone.0136492&representation=PDF
http://www.biomedcentral.com/1741-7015/13/242
(http://dx.doi.org/10.1186/s12916-015-0462-9)
http://www.biomedcentral.com/content/pdf/s12916-015-0462-9.pdf
http://www.biomedcentral.com/1471-2261/15/102
(http://dx.doi.org/10.1186/s12872-015-0096-z)
http://www.biomedcentral.com/content/pdf/s12872-015-0096-z.pdf
http://www.biomedcentral.com/1741-7015/13/241
(http://dx.doi.org/10.1186/s12916-015-0479-0)
http://www.biomedcentral.com/content/pdf/s12916-015-0479-0.pdf
http://www.biomedcentral.com/1471-2407/15/179
(http://dx.doi.org/10.1186/s12885-015-1102-7)
http://www.biomedcentral.com/content/pdf/s12885-015-1102-7.pdf
http://www.nejm.org/doi/full/10.1056/NEJMsa1502403?query=featured_home#t=articleTop
(http://dx.doi.org/10.1056/NEJMsa1502403)
http://www.nejm.org/doi/pdf/10.1056/NEJMsa1502403
http://www.nature.com/nm/journal/v12/n8/abs/nm1446.html
(http://dx.doi.org/10.1038/nm1446)
http://www.nature.com/nm/journal/v12/n8/pdf/nm1446.pdf
http://www.nature.com/ni/journal/v16/n1/full/ni.3043.html
(http://dx.doi.org/10.1038/ni.3043)
http://www.nature.com/ni/journal/v16/n1/pdf/ni.3043.pdf