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 0x47 0x1F 0x05
2: PCDATA invalid Char value 31
3: PCDATA invalid Char value 5
4: Opening and ending tag mismatch: AuthorList line 2321 and Chemical
5: Opening and ending tag mismatch: Chemical line 2357 and Affiliation
6: Opening and ending tag mismatch: Article line 2297 and AffiliationInfo
7: Opening and ending tag mismatch: MedlineCitation line 2285 and Author
8: Opening and ending tag mismatch: PubmedArticle line 2284 and AuthorList
9: Opening and ending tag mismatch: PubmedArticleSet line 3 and Article
10: 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 0xF3 0x61 0xBA
2: Unescaped '<' not allowed in attributes values
3: attributes construct error
4: Couldn't find end of Start Tag QualifierName line 2475
5: expected '>'
6: Opening and ending tag mismatch: ArticleId line 3136 and unparseable
7: Opening and ending tag mismatch: ArticleIdList line 3132 and Reference
8: expected '>'
9: Opening and ending tag mismatch: ArticleIdList line 3152 and Ar
10: Opening and ending tag mismatch: Reference line 3150 and ArticleIdList
11: Opening and ending tag mismatch: PubmedData line 3092 and Reference
12: Opening and ending tag mismatch: PubmedArticle line 2884 and ReferenceList
13: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedData
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