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: 0xB4 0x6F 0x3F 0x9B
2: Opening and ending tag mismatch: ArticleId line 2090 and Reference
3: Opening and ending tag mismatch: ArticleIdList line 2089 and ReferenceList
4: Opening and ending tag mismatch: Reference line 2087 and PubmedData
5: Opening and ending tag mismatch: ReferenceList line 1918 and PubmedArticle
6: PCDATA invalid Char value 1
7: Opening and ending tag mismatch: AbstractText line 2785 and Author
8: Opening and ending tag mismatch: Affiliation line 2801 and Author
9: Opening and ending tag mismatch: AffiliationInfo line 2800 and AuthorList
10: Opening and ending tag mismatch: Author line 2796 and Article
11: Opening and ending tag mismatch: Abstract line 2784 and MedlineCitation
12: Opening and ending tag mismatch: Article line 2764 and PubmedArticle
13: expected '>'
14: Opening and ending tag mismatch: AffiliationInfo line 3447 and Author
15: expected '>'
16: Opening and ending tag mismatch: AuthorList line 3442 and Article
17: Opening and ending tag mismatch: Article line 3419 and MedlineCitation
18: Opening and ending tag mismatch: MedlineCitation line 3407 and PubmedArticle
19: expected '>'
20: Premature end of data in tag MedlineCitation line 2757
21: Premature end of data in tag PubmedArticle line 2756
22: Premature end of data in tag PubmedData line 1871
23: Premature end of data in tag PubmedArticle line 1589
24: 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: 0xA4 0xE4 0x39 0xB7
2: error parsing attribute name
3: attributes construct error
4: Couldn't find end of Start Tag Descr line 2515
5: expected '>'
6: PCDATA invalid Char value 29
7: PCDATA invalid Char value 3
8: PCDATA invalid Char value 27
9: PCDATA invalid Char value 20
10: PCDATA invalid Char value 7
11: PCDATA invalid Char value 22
12: PCDATA invalid Char value 4
13: PCDATA invalid Char value 30
14: PCDATA invalid Char value 3
15: PCDATA invalid Char value 25
16: PCDATA invalid Char value 27
17: PCDATA invalid Char value 2
18: PCDATA invalid Char value 3
19: PCDATA invalid Char value 1
20: Opening and ending tag mismatch: ArticleIdList line 3183 and Reference
21: expected '>'
22: Opening and ending tag mismatch: ArticleId line 3204 and Art
23: expected '>'
24: Opening and ending tag mismatch: ReferenceList line 3144 and PubmedData
25: Opening and ending tag mismatch: PubmedData line 3098 and PubmedArticle
26: expected '>'
27: Opening and ending tag mismatch: ReferenceList line 3682 and PubmedData
28: Opening and ending tag mismatch: PubmedData line 3651 and PubmedArticle
29: expected '>'
30: Premature end of data in tag PubmedArticle line 2890
31: Premature end of data in tag PubmedArticleSet line 3

--- 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