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 0xB3 0x06 0xC2
2: PCDATA invalid Char value 6
3: Opening and ending tag mismatch: Citation line 934 and Reference
4: expected '>'
5: Opening and ending tag mismatch: ReferenceList line 740 and PubmedData
6: Opening and ending tag mismatch: PubmedData line 698 and PubmedArticle
7: Opening and ending tag mismatch: AbstractText line 1611 and AffiliationInfo
8: Opening and ending tag mismatch: Abstract line 1610 and Author
9: Opening and ending tag mismatch: AffiliationIfiliation line 1620 and AffiliationInfo
10: Opening and ending tag mismatch: Article line 1591 and AuthorList
11: Opening and ending tag mismatch: MedlineCitation line 1584 and Article
12: Opening and ending tag mismatch: PubmedArticle line 1583 and MedlineCitation
13: PCDATA invalid Char value 6
14: Opening and ending tag mismatch: Citation line 3342 and Reference
15: expected '>'
16: Opening and ending tag mismatch: ReferenceList line 3136 and PubmedData
17: Opening and ending tag mismatch: PubmedData line 3090 and PubmedArticle
18: expected '>'
19: Premature end of data in tag PubmedArticleSet line 3

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

--- re-building ‘easyPM_vignette_pdf.Rmd’ using rmarkdown
Warning in grep("\\\n$", msg) :
  input string 1 is invalid in this locale
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 0x63 0x35 0xF8
2: error parsing attribute name
3: attributes construct error
4: Couldn't find end of Start Tag PM<f0>c5<f8> line 2286
5: Opening and ending tag mismatch: MedlineCitation line 2285 and DateCompleted
6: Opening and ending tag mismatch: PubmedArticle line 2284 and MedlineCitation
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