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 0x51 0x97
2: PCDATA invalid Char value 19
3: expected '>'
4: Opening and ending tag mismatch: AffiliationInfo line 650 and Author
5: expected '>'
6: Opening and ending tag mismatch: AuthorList line 473 and Article
7: Opening and ending tag mismatch: Article line 451 and MedlineCitation
8: Opening and ending tag mismatch: MedlineCitation line 444 and PubmedArticle
9: Couldn't find end of Start Tag Citation line 1363
10: PCDATA invalid Char value 16
11: PCDATA invalid Char value 20
12: expected '>'
13: Opening and ending tag mismatch: ArticleId line 5488 and Art3
14: PCDATA invalid Char value 16
15: Opening and ending tag mismatch: PubmedData line 5460 and Reference
16: Opening and ending tag mismatch: PubmedArticle line 5267 and ReferenceList
17: Opening and ending tag mismatch: PubmedArticle line 443 and PubmedData
18: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedArticle
19: Extra content at the end of the document

--- 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 0x03 0xBC 0xBF
2: Couldn't find end of Start Tag Ci<f0> line 844
3: PCDATA invalid Char value 3
4: PCDATA invalid Char value 16
5: Opening and ending tag mismatch: AbstractText line 1582 and MedlineCitation
6: Opening and ending tag mismatch: Abstract line 1581 and PubmedArticle
7: Opening and ending tag mismatch: Citation line 5587 and Reference
8: Opening and ending tag mismatch: Reference line 5616 and ArticleId
9: Opening and ending tag mismatch: Reference line 5586 and ArticleIdList
10: Opening and ending tag mismatch: ReferenceList line 5483 and Reference
11: Opening and ending tag mismatch: PubmedData line 5452 and ReferenceList
12: Opening and ending tag mismatch: PubmedArticle line 5259 and PubmedData
13: Opening and ending tag mismatch: Article line 1562 and PubmedArticle
14: expected '>'
15: Opening and ending tag mismatch: NameOfSubstance line 5949 and NameOfSuba
16: PCDATA invalid Char value 16
17: Opening and ending tag mismatch: Citation line 6988 and Reference
18: expected '>'
19: Opening and ending tag mismatch: ReferenceList line 6800 and PubmedData
20: Opening and ending tag mismatch: PubmedData line 6768 and PubmedArticle
21: expected '>'
22: Premature end of data in tag Citation line 1555
23: Premature end of data in tag Reference line 1554
24: Premature end of data in tag ReferenceList line 1295
25: Premature end of data in tag PubmedData line 1254
26: Premature end of data in tag PubmedArticle line 1106
27: 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