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: Input is not proper UTF-8, indicate encoding !
Bytes: 0xF0 0x13 0x03 0x36
2: PCDATA invalid Char value 19
3: PCDATA invalid Char value 3
4: PCDATA invalid Char value 2
5: Opening and ending tag mismatch: Citation line 1920 and ArticleIdList
6: Opening and ending tag mismatch: ArticleIdList line 2009 and Reference
7: StartTag: invalid element name
8: PCDATA invalid Char value 20
9: PCDATA invalid Char value 3
10: PCDATA invalid Char value 2
11: Opening and ending tag mismatch: ArticleIdList line 2027 and Reference
12: expected '>'
13: Opening and ending tag mismatch: Reference line 1996 and PubmedData
14: Opening and ending tag mismatch: ReferenceList line 1918 and PubmedArticle
15: Specification mandate value for attribute UcEbVASY06m
16: attributes construct error
17: Couldn't find end of Start Tag Ci3 line 3352
18: PCDATA invalid Char value 16
19: Opening and ending tag mismatch: PubmedData line 1871 and PubmedArticleSet
20: Premature end of data in tag PubmedArticle line 1589
21: Premature end of data in tag PubmedArticleSet line 3

--- 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 0x03 0x1B 0x6D
2: PCDATA invalid Char value 3
3: PCDATA invalid Char value 27
4: Opening and ending tag mismatch: Citation line 814 and Reference
5: expected '>'
6: Opening and ending tag mismatch: ReferenceList line 746 and PubmedData
7: Opening and ending tag mismatch: PubmedData line 704 and PubmedArticle
8: PCDATA invalid Char value 16
9: Opening and ending tag mismatch: Citation line 1525 and Reference
10: expected '>'
11: Opening and ending tag mismatch: ReferenceList line 1295 and PubmedData
12: Opening and ending tag mismatch: PubmedData line 1254 and PubmedArticle
13: error parsing attribute name
14: attributes construct error
15: Couldn't find end of Start Tag Med line 1560
16: Opening and ending tag mismatch: PubmedArticle line 1559 and Citation
17: Opening and ending tag mismatch: PubmedArticle line 1106 and Reference
18: Opening and ending tag mismatch: PubmedArticle line 443 and ReferenceList
19: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedData
20: 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