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: Couldn't find end of Start Tag Ref line 3144
2: PCDATA invalid Char value 16
3: Input is not proper UTF-8, indicate encoding !
Bytes: 0x83 0x08 0x99 0xE9
4: PCDATA invalid Char value 8
5: Opening and ending tag mismatch: PubmedData line 3098 and Reference
6: Failed to parse QName 'Ci:'
7: error parsing attribute name
8: attributes construct error
9: Couldn't find end of Start Tag Ci:2708-23 line 3174
10: Opening and ending tag mismatch: Reference line 3173 and Citation
11: Opening and ending tag mismatch: PubmedArticle line 2890 and Reference
12: Opening and ending tag mismatch: PubmedArticleSet line 3 and ReferenceList
13: 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 0xB3 0x72 0x7B
2: PCDATA invalid Char value 24
3: Opening and ending tag mismatch: Reference line 2039 and ArticleIdList
4: Opening and ending tag mismatch: ReferenceList line 1918 and Reference
5: Opening and ending tag mismatch: PubmedData line 1871 and ReferenceList
6: Opening and ending tag mismatch: PubmedArticle line 1589 and PubmedData
7: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedArticle
8: 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