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 0x53 0x86 0x71
2: Opening and ending tag mismatch: AffiliationInfo line 1744 and Author
3: expected '>'
4: Opening and ending tag mismatch: AuthorList line 1619 and Article
5: Opening and ending tag mismatch: Article line 1597 and MedlineCitation
6: Opening and ending tag mismatch: MedlineCitation line 1590 and PubmedArticle
7: Specification mandate value for attribute T
8: attributes construct error
9: Couldn't find end of Start Tag ArticleId line 4871
10: Opening and ending tag mismatch: ArticleIdList line 4870 and Reference
11: expected '>'
12: Opening and ending tag mismatch: ReferenceList line 4435 and PubmedData
13: Opening and ending tag mismatch: PubmedData line 4396 and PubmedArticle
14: PCDATA invalid Char value 16
15: expected '>'
16: Opening and ending tag mismatch: ArticleIdList line 6301 and Reference
17: expected '>'
18: Opening and ending tag mismatch: ReferenceList line 6070 and PubmedData
19: Opening and ending tag mismatch: PubmedData line 6039 and PubmedArticle
20: expected '>'
21: Premature end of data in tag PubmedArticle line 4292
22: Premature end of data in tag PubmedArticle line 1589
23: 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 0xA3 0x6F 0x77
2: Opening and ending tag mismatch: Citation line 814 and Reference
3: expected '>'
4: Opening and ending tag mismatch: ReferenceList line 746 and PubmedData
5: Opening and ending tag mismatch: PubmedData line 704 and PubmedArticle
6: error parsing attribute name
7: attributes construct error
8: Couldn't find end of Start Tag Artic line 1514
9: Opening and ending tag mismatch: Reference line 1512 and ArticleIdList
10: Opening and ending tag mismatch: ReferenceList line 1295 and Reference
11: expected '>'
12: Opening and ending tag mismatch: ArticleIdList line 1531 and Ar
13: Opening and ending tag mismatch: Reference line 1529 and ArticleIdList
14: Opening and ending tag mismatch: PubmedData line 1254 and Reference
15: Opening and ending tag mismatch: PubmedArticle line 1106 and ReferenceList
16: Opening and ending tag mismatch: PubmedArticle line 443 and PubmedData
17: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedArticle
18: 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