Error(s) in re-building vignettes:
  ...
duplicated vignette title:
  ‘Retrieving and Analyzing PubMed Records via easyPubMed’

--- re-building ‘easyPM_vignette_html.Rmd’ using rmarkdown
Quitting from lines 39-50 (easyPM_vignette_html.Rmd) 
Error: processing vignette 'easyPM_vignette_html.Rmd' failed with diagnostics:
1: expected '>'
2: Input is not proper UTF-8, indicate encoding !
Bytes: 0xF0 0x63 0x33 0xD7
3: Opening and ending tag mismatch: ReferenceList line 746 and Reference
4: Opening and ending tag mismatch: PubmedData line 704 and ReferenceList
5: Opening and ending tag mismatch: PubmedArticle line 443 and PubmedData
6: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedArticle
7: Extra content at the end of the document

--- failed re-building ‘easyPM_vignette_html.Rmd’

--- re-building ‘easyPM_vignette_pdf.Rmd’ using rmarkdown
Quitting from lines 39-50 (easyPM_vignette_pdf.Rmd) 
Error: processing vignette 'easyPM_vignette_pdf.Rmd' failed with diagnostics:
1: Input is not proper UTF-8, indicate encoding !
Bytes: 0xF0 0xA3 0x0B 0xB9
2: PCDATA invalid Char value 11
3: Opening and ending tag mismatch: ArticleTitle line 1129 and Article
4: Opening and ending tag mismatch: Article line 1114 and MedlineCitation
5: Opening and ending tag mismatch: MedlineCitation line 1107 and PubmedArticle
6: Opening and ending tag mismatch: Author line 1747 and AffiliationInfo
7: Opening and ending tag mismatch: AuthorList line 1619 and Author
8: Opening and ending tag mismatch: Author line 1755 and ForeName
9: Opening and ending tag mismatch: Article line 1597 and Author
10: Opening and ending tag mismatch: MedlineCitation line 1590 and AuthorList
11: Opening and ending tag mismatch: PubmedArticle line 1589 and Article
12: Opening and ending tag mismatch: PubmedArticle line 1106 and MedlineCitation
13: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedArticle
14: Extra content at the end of the document

--- failed re-building ‘easyPM_vignette_pdf.Rmd’

SUMMARY: processing the following files failed:
  ‘easyPM_vignette_html.Rmd’ ‘easyPM_vignette_pdf.Rmd’

Error: Vignette re-building failed.
Error: Duplicate vignette titles.
  Ensure that the %\VignetteIndexEntry lines in the vignette sources
  correspond to the vignette titles.
Execution halted