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 0x73 0x75 0x43
2: Opening and ending tag mismatch: Reference line 2602 and ArticleIdList
3: Opening and ending tag mismatch: ReferenceList line 2589 and Reference
4: Opening and ending tag mismatch: PubmedData line 2542 and ReferenceList
5: Opening and ending tag mismatch: PubmedArticle line 2290 and PubmedData
6: Opening and ending tag mismatch: PubmedArticleSet line 3 and PubmedArticle
7: 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 0xC3 0xA8 0xA1
2: error parsing attribute name
3: attributes construct error
4: Couldn't find end of Start Tag Articl<f0><c3> line 942
5: Opening and ending tag mismatch: AbstractText line 1617 and AffiliationInfo
6: Opening and ending tag mismatch: Abstract line 1616 and Author
7: Opening and ending tag mismatch: Article line 1597 and Affiliation
8: Opening and ending tag mismatch: MedlineCitation line 1590 and AffiliationInfo
9: Opening and ending tag mismatch: PubmedArticle line 1589 and Author
10: Opening and ending tag mismatch: PubmedArticleSet line 3 and AuthorList
11: 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